/** \mainpage Fish user documentation \section introduction The friendly interactive shell This is the documentation for \c fish, the friendly interactive shell. \c fish is a user friendly commandline shell intended mostly for interactive use. A shell is a program used to execute other programs. For the latest information on \c fish, please visit the fish homepage. \section syntax Syntax overview Shells like fish are used by giving them commands. Every \c fish command follows the same simple syntax. A command is executed by writing the name of the command followed by any arguments. Example: echo hello world calls the \c echo command. \c echo is a command which will write its arguments to the screen. In the example above, the output will be 'hello world'. Everything in fish is done with commands. There are commands for performing a set of commands multiple times, commands for assigning variables, commands for treating a group of commands as a single command, etc.. And every single command follows the same simple syntax. If you wish to find out more about the echo command used above, read the manual page for the echo command by writing: man echo \c man is a command for displaying a manual page on a given topic. There are manual pages for almost every command on most computers. There are also manual pages for many other things, such as system libraries and important files. Every program on your computer can be used as a command in \c fish. If the program file is located in one of the directories in the PATH, it is sufficient to type the name of the program to use it. Otherwise the whole filename, including the directory (like \c /home/me/code/checkers/checkers or \c ../checkers) has to be used. Here is a list of some useful commands: - \c cd, change the current directory - \c ls, list the contents of a directory - \c man, print a manual page - \c mv, move files - \c cp, copy files - \c open, open files with the default application associated with each filetype - \c less, read the contents of files Commands and parameters are separated by the space character ( ). Every command ends with either a newline (i.e. by pressing the return key) or a semicolon (;). More than one command can be written on the same line by separating them with semicolons. \subsection quotes Quotes Sometimes features such as parameter expansion and character escapes get in the way. When that happens, the user can write a parameter within quotes, either ' (single quote) or " (double quote). There is one important difference between single quoted and double quoted strings: When using double quoted string, variable expansion still takes place. Other than that, a quoted parameter will not be parameter expanded, may contain spaces, and escape sequences are ignored. Single quotes have no special meaning withing double quotes and vice versa. Example: rm "cumbersome filename.txt" Will remove the file 'cumbersome filename.txt', while rm cumbersome filename.txt would remove the two files 'cumbersome' and 'filenmae.txt'. \subsection escapes Escaping characters Some characters can not be written directly on the command line. For these characters, so called escape sequences are provided. These are: - '\\n', escapes a newline character - '\\t', escapes the tab character - '\\b', escapes the backspace character - '\\r', escapes the carriage return character - '\\e', escapes the escape character - '\\ ', escapes the space character - '\\$', escapes the dollar character - '\\\\', escapes the backslash character - '\\*', escapes the star character - '\\?', escapes the question mark character - '\\~', escapes the tilde character - '\\#', escapes the hash character - '\\(', escapes the left parenthesis character - '\\)', escapes the right parenthesis character - '\\{', escapes the left curly bracket character - '\\}', escapes the right curly bracket character - '\\[', escapes the left bracket character - '\\]', escapes the right bracket character - '\\\<', escapes the less than character - '\\\>', escapes the more than character - '\\^', escapes the circumflex character - '\\xxx', where xx is a hexadecimal number, escapes the ascii character with the specified value - '\\oooo', where ooo is an octal number, escapes the ascii character with the specified value - '\\uxxxx', where xxxx is a hexadecimal number, escapes the 16-bit unicode character with the specified value - '\\Uxxxxxxxx', where xxxxxxxx is a hexadecimal number, escapes the 32-bit unicode character with the specified value \subsection redirects IO redirection Most program use three types of input/output (IO), each represented by a number called a file descriptor (FD). These are: - Standard input, FD 0, for reading, defaults to reading from the keyboard. - Standard output, FD 1, for writing, defaults to writing to the screen. - Standard error, FD 2, for writing errors and warnings, defaults to writing to the screen. The reason for providing for two methods of output is that errors and warnings can be separated from regular program output. Any file descriptor can be directed to a different output than it's default through a simple mechanism called a redirection. An example of a file redirection is echo hello \>output.txt, which directs the output of the echo command to the file error.txt. - To redirect standard input, write \ - To redirect standard output, write \>DESTINATION - To redirect standard error, write ^DESTINATION - To redirect standard output to a file which will be appended, write \>\>DESTINATION_FILE - To redirect standard error to a file which will be appended, write ^^DESTINATION_FILE DESTINATION can be one of the following: - A filename. The output will be written to the specified file. - An ampersand (\&) followed by the number of another file descriptor. The file descriptor will be a duplicate of the specified file descriptor. - A minus sign (-). The file descriptor will be closed. Example: To redirect both standard output and standard error to the file all_output.txt, you can write echo Hello \>all_output.txt ^\&1. Any FD can be redirected in an arbitrary way by prefixing the redirection with the number of the FD. - To redirect input of FD number N, write N\ - To redirect output of FD number N, write N\>DESTINATION - To redirect output of FD number N to a file which will be appended, write N\>\>DESTINATION_FILE Example: echo Hello 2\>- and echo Hello ^- are equivalent. \subsection piping Piping The user can string together multiple commands into a so called pipeline. This means that the standard output of one command will be read in as standard input into the next command. This is done by separating the commands by the pipe character (|). For example cat foo.txt | head will call the 'cat' program with the parameter 'foo.txt', which will print the contents of the file 'foo.txt'. The contents of foo.txt will then be filtered through the program 'head', which will pass on the first ten lines of the file to the screen. For more information on how to combine commands through pipes, read the manual pages of the commands you want to use using the 'man' command. If you want to find out more about the 'cat' program, type man cat. Pipes usually connect file descriptor 1 (standard output) of the first process to file descriptor 0 (standard input) of the second process. It is possible use a different output file descriptor by prepending the desired FD number and then output redirect symbol to the pipe. For example: make fish 2>|less will attempt to build the fish program, and any errors will be shown using the less pager. \subsection syntax-background Background jobs When you start a job in \c fish, \c fish itself will pause, and give control of the terminal to the program just started. Sometimes, you want to continue using the commandline, and have the job run in the background. To create a background job, append a \& (ampersand) to your command. This will tell fish to run the job in the background. \subsection syntax-job-control Job control Most programs allow you to suspend the programs execution and return control to \c fish by Pressing ^Z (Press and hold the Control key and press 'z'). Once back at the \c fish commandline, you can start other programs and do anything you want. If you then want to go back to the suspended command by using the fg command. If you instead want to put a suspended job into the foreground, use the fg command. To get a listing of all currently started jobs, use the jobs command. \subsection syntax-words Some common words This is a short explanation of some of the commonly used words in fish. - argument, a parameter given to a command - builtin, a command that is implemented as part of the shell - command, a program - function, a block of one or more fish commands that can be called as a single command. By using functions, it is possible to string together multiple smaller commands into one more advanced command. - job, a running pipeline or command - pipeline, a set of commands stringed together so that the output of one command is the input of the next command - redirection, a operation that changes one of the input/output streams associated with a job \section help Help \c fish has an extensive help system. Use the help command to obtain help on a specific subject or command. For instance, writing help syntax displays the syntax section of this documentation. Help on a specific builtin can also be obtained with the -h parameter. For instance, to obtain help on the \c fg builtin, either type fg -h or help fg. \section completion Tab completion Tab completion is one of the most time saving features of any modern shell. By tapping the tab key, the user asks \c fish to guess the rest of the command or parameter that the user is currently typing. If \c fish can only find one possible completion, \c fish will write it out. If there is more than one completion, \c fish will write out the longest common prefix that all completions have in common. If all completions differ on the first character, a list of all possible completions is printed. The list features descriptions of the completions and if the list doesn't fit the screen, it is scrollable by using the arrow keys, the page up/page down keys or the space bar. Press any other key will exit the list and insert the pressed key into the command line. These are the general purpose tab completions that \c fish provides: - Completion of commands, both builtins, functions and regular programs. - Completion of environment variable names. - Completion of usernames for tilde expansion. - Completion of filenames, even on strings with wildcards such as '*' and '?'. - Completion of job id, job name and process names for process expansion. \c fish provides a large number of program specific completions. Most of these completions are simple options like the \c -l option for \c ls, but some are more advanced. The latter include: - The programs 'man' and 'whatis' show all installed manual pages as completions. - The 'make' program uses all targets in the Makefile in the current directory as completions. - The 'mount' command uses all mount points specified in fstab as completions. - The 'ssh' command uses all hosts in that are stored in the known_hosts file as completions. (see the ssh documentation for more information) - The 'su' command uses all users on the system as completions. - The \c apt-get, \c rpm and \c yum commands use all installed packages as completions. \subsection completion-own Writing your own completions Specifying your own completions is not complicated. To specify a completion, use the \c complete command. \c complete takes as a parameter the name of the command to specify a completion for. For example, to add a completion for the program \c myprog, one would start the completion command with complete -c myprog .... To provide a list of possible completions for myprog, use the \c -a switch. If \c myprog accepts the arguments start and stop, this can be specified as complete -c myprog -a 'start stop'. The argument to the \c -a switch is always a single string. At completion time, it will be tokenized on spaces and tabs, and variable expansion, command substitution and other forms of parameter expansion will take place. Fish has a special syntax to support specifying switches accepted by a command. The switches \c -s, \c -l and \c -o are used to specify a short switch (single character, such as -l), a gnu style long switch (such as --color) and an old-style long switch (like -shuffle), respectively. If the command 'myprog' has an option '-o' which can also be written as '--output', and which can take an additional value of either 'yes' or 'no', this can be specified by writing: complete -c myprog -s o -l output -a "yes no" There are also special switches for specifying that a switch requires an argument, to disable filename completion, to create completions that are only available in some combinations, etc.. For a complete description of the various switches accepted by the \c complete command, see the documentation for the complete builtin, or write 'complete --help' inside the \c fish shell. For examples of how to write your own complex completions, study the completions in /etc/fish.d/completions (or ~/etc/fish.d/completions if you installed fish in your home directory). If you wish to use a completion, you should consider adding it to your startup files. When completion has been requested for a command \c COMMAND, fish will automatically look for the file ~/.fish.d/completions/COMMAND.fish. If it exists, it will be automatically loaded. If you have written new completions for a common Unix command, please consider sharing your work by sending it to the fish mailinglist. \section expand Parameter expansion (Globbing) When an argument for a program is given on the commandline, it undergoes the process of parameter expansion before it is sent on to the command. There are many ways in which the user can specify a parameter to be expanded. These include: \subsection expand-wildcard Wildcards If a star (*) or a question mark (?) is present in the parameter, \c fish attempts to match the given parameter to any files in such a way that '?' can match any character except '/' and '*' can match any string of characters not containing '/'. Example: a* matches any files beginning with an 'a' in the current directory. ??? matches any file in the current directory whose name is exactly three characters long. If no matches are found for a specific wildcard, it will expand into zero arguments, i.e. to nothing. If none of the wildcarded arguments sent to a command result in any matches, the command will not be executed. If this happens when using the shell interactively, a warning will also be printed. \subsection expand-command-substitution Command substitution If a parameter contains a set of parenthesis, the text enclosed by the parenthesis will be interpreted as a list of commands. Om expansion, this list is executed, and substituted by the output. If the output is more than one line long, each line will be expanded to a new parameter. Example: The command echo (basename image.jpg .jpg).png will output 'image.png'. The command for i in *.jpg; convert $i (basename $i .jpg).png; end will convert all Jpeg files in the current directory to the PNG format. \subsection expand-brace Brace expansion A comma separated list of characters enclosed in curly braces will be expanded so each element of the list becomes a new parameter. Example: echo input.{c,h,txt} outputs 'input.c input.h input.txt' The command mv *.{c,h} src/ moves all files with the suffix '.c' or '.h' to the subdirectory src. \subsection expand-variable Variable expansion A dollar sign followed by a string of characters is expanded into the value of the environment variable with the same name. For an introduction to the concept of environment variables, read the Environment variables section. Example: echo \$HOME prints the home directory of the current user. If you wish to combine environment variables with text, you can encase the variables within braces to embed a variable inside running text like echo Konnichiwa {$USER}san, which will print a personalized Japanese greeting. The {$USER}san syntax might need a bit of an elaboration. Posix shells allow you to specify a variable name using '$VARNAME' or '${VARNAME}'. Fish only supports the former, but has no support whatsoever for the latter or anything remotely like it. So what is '{$VARNAME}' then? Well, '{WHATEVER}' is brace expansion, the same as supported by Posix shells, i.e. 'a{b,c}d' -> 'abd acd' works both in bash and on fish. So '{$VARNAME}' is a bracket-expansion with only a single element, i.e. it becomes expanded to '$VARNAME', which will be variable expanded to the value of the variable 'VARNAME'. So you might think that the brackets don't actually do anything, and that is nearly the truth. The snag is that there once along the way was a '}' in there somewhere, and } is not a valid character in a variable name. So anything after the otherwise pointless bracket expansion becomes NOT a part of the variable name, even if it happens to be a legal variable name character. That's why '{$USER}san' looks for the variable '$USER' and not for the variable '$USERsan'. It's a case of one syntax lending itself nicely to solving an unrelated problem in it's spare time. Variable expansion is the only type of expansion performed on double quoted strings. There is, however, an important difference in how variables are expanded when quoted and when unquoted. An unquoted variable expansion will result in a variable number of arguments. For example, if the variable $foo has zero elements or is undefined, the argument $foo will expand to zero elements. If the variable $foo is an array of five elements, the argument $foo will expand to five elements. When quoted, like "$foo", a variable expansion will always result in exactly one argument. Undefined variables will expand to the empty string, and array variables will be concatenated using the space character. \subsection expand-home Home directory expansion The ~ (tilde) character at the beginning of a parameter, followed by a username, is expanded into the home directory of the specified user. A lone ~, or a ~ followed by a slash, is expanded into the home directory of the process owner. \subsection expand-process Process expansion The \% (percent) character at the beginning of a parameter followed by a string is expanded into a process id. The following expansions are performed: - If the string is the entire word \c self, the shells pid is the result - Otherwise, if the string is the id of a job, the result is the process group id of the job. - Otherwise, if any child processes match the specified string, their pids are the result of the expansion. - Otherwise, if any processes owned by the user match the specified string, their pids are the result of the expansion. This form of expansion is useful for commands like kill and fg, which take the process ids as an argument. Example: fg \%ema will search for a process whose command line begins with the letters 'ema', such as emacs, and if found, put it in the foreground. kill -s SIGINT \%3 will send the SIGINT signal to the job with job id 3. \subsection combine Combining different expansions All of the above expansions can be combined. If several expansions result in more than one parameter, all possible combinations are created. Example: If the current directory contains the files 'foo' and 'bar', the command echo a(ls){1,2,3} will output 'abar1 abar2 abar3 afoo1 afoo2 afoo3'. \section variables Environment variables The concept of environment variables are central to any shell. Environment variables are variables, whose values can be set and used by the user. For information on how to use the current value of a variable, see the section on variable expansion. To set a variable value, use the \c set command. Example: To set the variable \c smurf to the value \c blue, use the command set smurf blue. After a variable has been set, you can use the value of a variable in the shell through variable expansion. Example: To use the value of a the variable \c smurf, write $ (dollar symbol) followed by the name of the variable, like echo Smurfs are $smurf, which would print the result 'Smurfs are blue'. \subsection variables-scope Variable scope There are three kinds of variables in fish, universal, global and local variables. Universal variables are shared between all fish sessions a user is running on one computer. Global variables are specific to the current fish session, but are not associated with any specific block scope, and will never be erased unless the user explicitly requests it using set -e. Local variables are specific to the current fish session, and associated with a specific block of commands, and is automatically erased when a specific block goes out of scope. A block of commands is a series of commands that begins with one of the commands \c 'for, \c 'while' , \c 'if', \c 'function', \c 'begin' or \c 'switch', and ends with the command \c 'end'. The user can specify that a variable should have either global or local scope using the \c -g/--global or \c -l/--local switches. Variables can be explicitly set to be universal with the \c -U or \c --universal switch, global with the \c -g or \c --global switch, or local with the \c -l or \c --local switch. The scoping rules when creating or updating a variable are: -# If a variable is explicitly set to either universal, global or local, that setting will be honored -# If a variable is not explicitly set to be either universal, global or local, but has been previously defined, the variable scope is not changed -# If a variable is not explicitly set to be either universal, global or local and has never before been defined, the variable will be local to the currently executing functions. If no function is executing, the variable will be global. There may be many variables with the same name, but different scopes. When using a variable, the variable scope will be searched from the inside out, i.e. a local variable will be used rather than a global variable with the same name, a global variable will be used rather than a universal variable with the same name. Example: The following code will not output anything: 
begin
	# This is a nice local scope where all variables will die
	set -l pirate 'There be treasure in them thar hills'
end

# This will not output anything, since the pirate was local
echo $pirate
\subsection variables-universal More on universal variables Universal variables are variables that are shared between all the users fish sessions on the computer. Fish stores many of it's configuration options as universal variables. This means that in order to change fish settings, all you have to do is change the variable value once, and it will be automatically updated for all sessions, and preserved across computer reboots and login/logout. To see universal variables in action, start two fish sessions side by side, and issue the following command in one of them set fish_color_cwd blue. Since \c fish_color_cwd is a universal variable, the color of the current working directory listing in the prompt will instantly change to blue on both terminals. \subsection variables-functions Variable scope for functions When calling a function, all non-global variables temporarily disappear. This shadowing of the local scope is needed since the variable namespace would become cluttered, making it very easy to accidentally overwrite variables from another function. For example, the following code will output 'Avast, mateys': 
function shiver
	set phrase 'Shiver me timbers'
end

function avast
	set phrase 'Avast, mateys'

	# Calling the shiver function here can not change any variables
	# in the local scope
	shiver

	echo $phrase
end

avast
\subsection variables-export Exporting variables Variables in fish can be exported. This means the variable will be inherited by any commands started by fish. It is convention that exported variables are in uppercase and unexported variables are in lowercase. Variables can be explicitly set to be exported with the \c -x or \c --export switch, or not exported with the \c -u or \c --unexport switch. The exporting rules when creating or updating a variable are identical to the scoping rules for variables: -# If a variable is explicitly set to either be exported or not exported, that setting will be honored -# If a variable is not explicitly set to be exported or not exported, but has been previously defined, the previous exporting rule for the variable is kept -# If a variable is not explicitly set to be either global or local and has never before been defined, the variable will not be exported \subsection variables-arrays Arrays \c fish can store a list of multiple strings inside of a variable. To access one element of an array, use the index of the element inside of square brackets, like this: 
echo $PATH[3]
If you do not use any brackets, all the elements of the array will be written as separate items. This means you can easily iterate over an array using this syntax: 
for i in $PATH; echo $i is in the path; end
To create a variable \c smurf, containing the items \c blue and \c small, simply write: 
set smurf blue small
It is also possible to set or erase individual elements of an array: 
\#Set smurf to be an array with the elements 'blue' and 'small'
set smurf blue small

\#Change the second element of smurf to 'evil'
set smurf[2] evil

\#Erase the first element
set -e smurf[1]

\#Output 'evil'
echo $smurf
\subsection variables-special Special variables The user can change the settings of \c fish by changing the values of certain environment variables. - \c BROWSER, which is the users preferred web browser. If this variable is set, fish will use the specified browser instead of the system default browser to display the fish documentation. - \c CDPATH, which is an array of directories in which to search for the new directory for the \c cd builtin. - \c fish_color_normal, \c fish_color_command, \c fish_color_substitution, \c fish_color_redirection, \c fish_color_end, \c fish_color_error, \c fish_color_param, \c fish_color_comment, \c fish_color_match, \c fish_color_search_match, \c fish_color_cwd, \c fish_pager_color_prefix, \c fish_pager_color_completion, \c fish_pager_color_description and \c fish_pager_color_progress are used to change the color of various elements in \c fish. These variables are universal, i.e. when changing them, their new value will be used by all running fish sessions. The new value will also be retained when restarting fish. - \c PATH, which is an array of directories in which to search for commands - \c umask, which is the current file creation mask. The preferred way to change the umask variable is through the umask shellscript function. An attempt to set umask to an invalid value will always fail. \c fish also sends additional information to the user through the values of certain environment variables. The user can not change the values of these variables. They are: - \c _, which is the name of the currently running command. - \c history, which is an array containing the last commands that where entered. - \c HOME, which is the users home directory. This variable can only be changed by the root user. - \c PWD, which is the current working directory. - \c status, which is the exit status of the last foreground job to exit. If a job contains pipelines, the status of the last command in the pipeline is the status for the job. - \c USER, which is the username. This variable can only be changed by the root user. - \c LANG, \c LC_ALL, \c LC_COLLATE, \c LC_CTYPE, \c LC_MESSAGES, \c LC_MONETARY, \c LC_NUMERIC and \c LC_TIME set the language option for the shell and subprograms. See the section Locale variables for more information. Variables whose name are in uppercase are exported to the commands started by fish. This rule is not enforced by fish, but it is good coding practice to use casing to distinguish between exported and unexported variables. \c fish also uses several variables internally. Such variables are prefixed with the string __FISH or __fish. These should be ignored by the user. \subsection variables-locale Locale variables The most common way to set the locale to use a command like 'set -x LANG en_GB.utf8', which sets the current locale to be the english language, as used in Great Britain, using the UTF-8 character set. For a list of available locales, use 'locale -a'. \c LANG, \c LC_ALL, \c LC_COLLATE, \c LC_CTYPE, \c LC_MESSAGES, \c LC_MONETARY, \c LC_NUMERIC and LC_TIME set the language option for the shell and subprograms. These variables work as follows: \c LC_ALL forces all the aspects of the locale to the specified value. If LC_ALL is set, all other locale variables will be ignored. The other LC_ variables set the specified aspect of the locale information. LANG is a fallback value, it will be used if none of the LC_ variables are specified. \section builtin-overview Builtins Many other shells have a large library of builtin commands. Most of these commands are also available as standalone commands, but have been implemented in the shell anyway for whatever reason. To avoid code duplication, and to avoid the confusion of subtly differing versions of the same command, \c fish only implementing builtins for actions which cannot be performed by a regular command. \section bundle Commands bundled with fish The following commands are distributed with fish. Many of them are builtins or shellscript functions, and can only be used inside fish. - ., read and execute the commands in a file - and, execute command if previous command suceeded - bg, set a command to the background - begin, execute a block of commands - bind, change keyboard bindings - break, stop the execution of a loop - block, Temporarily block delivery of events - builtin, execute a builtin command - case, conditionally execute a block of commands - cd, change the current directory - command, execute an external program - commandline, set or get the contents of the commandline buffer - complete, add and remove completions - continue, skip the rest of the current lap of a loop - count, count the number of arguments - dirh, view the directory history - dirs, view the directory stack - end, end a block of commands - else, conditionally execute a block of commands - eval, evaluate a string as a command - exec, replace the current process image with a new command - exit, causes \c fish to quit - fg, set a command to the foreground - fishd, the universal variable daemon - for, perform a block of commands once for every element in a list - function, define a new function - functions, print or erase functions - help, show the fish documentation - if, conditionally execute a block of commands - jobs, print the currently running jobs - mimedb, view mimedata about a file - nextd, move forward in the directory history - not, negates the exit status of any command - or, execute a command if previous command failed - popd, move to the topmost directory on the directory stack - prevd, move backwards in the direcotry stack - pushd, push the surrent directory onto the directory stack - random, calculate a pseudo-random number - return, return from a function - read, read from a stream into an environment variable - set, set environment variables - set_color, change the terminal colors - switch, conditionally execute a block of commands - tokenize, split a string up into multiple tokens - ulimit, set or get the shells resurce usage limits - umask, set or get the file creation mask - while, perform a block of commands while a condition is met For more information about these commands, use the --help option of the command to display a longer explanation. \section editor Command Line editor The \c fish editor features copy and paste, a searchable history and many editor functions that can be bound to special keyboard shortcuts. The most important keybinding is probably the tab key, which is bound to the complete function. Here are some of the commands available in the editor: - Tab completes the current token - Home or Ctrl-a moves to the beginning of the line - End or Ctrl-e moves to the end of line - Left and right moves one character left or right - Alt-left and Alt-right moves one word left or right, or moves forward/backward in the directory history if the commandline is empty - Up and down search the command history for the previous/next command containing the string that was specified on the commandline before the search was started. If the commandline was empty when the search started, all commands match. See the history section for more information on history searching. - Alt-up and Alt-down search the command history for the previous/next token containing the token under the cursor before the search was started. If the commandline was not on a token when the search started, all tokens match. See the history section for more information on history searching. - Delete and backspace removes one character forwards or backwards - Ctrl-c delete entire line - Ctrl-d delete one character to the right of the cursor, unless the buffer is empty, in which case the shell will exit - Ctrl-k move contents from the cursor to the end of line to the killring - Ctrl-u move contents from the beginning of line to the cursor to the killring - Ctrl-l clear and repaint screen - Ctrl-w move previous word to the killring - Alt-d move next word to the killring - Alt-w prints a short description of the command under the cursor - Alt-l lists the contents of the current directory, unless the cursor is over a directory argument, in which case the contents of that directory will be listed - Alt-p adds the string '| less;' to the end of the job under the cursor. The result is that the output of the command will be paged. You can change these key bindings by making an inputrc file. To do this, copy the file /etc/fish_inputrc to your home directory and rename it to '.fish_inputrc'. Now you can edit the file .fish_inputrc, to change your key bindings. The fileformat of this file is described in the manual page for readline. Use the command man readline to read up on this syntax. Please note that the list of key binding functions in fish is different to that offered by readline. Currently, the following functions are available: - \c backward-char, moves one character to the left - \c backward-delete-char, deletes one character of input to the left of the cursor - \c backward-kill-line, move everything from the beginning of the line to the cursor to the killring - \c backward-kill-word, move the word to the left of the cursor to the killring - \c backward-word, move one word to the left - \c beginning-of-history, move to the beginning of the history - \c beginning-of-line, move to the beginning of the line - \c complete, guess the remainder of the current token - \c delete-char, delete one character to the right of the cursor - \c delete-line, delete the entire line - \c dump-functions, print a list of all key-bindings - \c end-of-history, move to the end of the history - \c end-of-line, move to the end of the line - \c explain, print a description of possible problems with the current command - \c forward-char, move one character to the right - \c forward-word, move one word to the right - \c history-search-backward, search the history for the previous match - \c history-search-forward, search the history for the next match - \c kill-line, move everything from the cursor to the end of the line to the killring - \c kill-whole-line, move the line to the killring - \c kill-word, move the next word to the killring - \c yank, insert the latest entry of the killring into the buffer - \c yank-pop, rotate to the previous entry of the killring You can also bind a pice of shellscript to a key using the same syntax. For example, the Alt-p functionality described above is implemented using the following keybinding. 
"\M-p": if commandline -j|grep -v 'less *$' >/dev/null; commandline -aj "|less;"; end
\subsection killring Copy and paste (Kill Ring) \c fish uses an Emacs style kill ring for copy and paste functionality. Use Ctrl-K to cut from the current cursor position to the end of the line. The string that is cut (a.k.a. killed) is inserted into a linked list of kills, called the kill ring. To paste the latest value from the kill ring use Ctrl-Y. After pasting, use Meta-Y to rotate to the previous kill. If the environment variable DISPLAY is set, \c fish will try to connect to the X-windows server specified by this variable, and use the clipboard on the X server for copying and pasting. \subsection history Searchable history After a command has been entered, it is inserted at the end of a history list. Any duplicate history items are automatically removed. By pressing the up and down keys, the user can search forwards and backwards in the history. If the current command line is not empty when starting a history search, only the commands containing the string entered into the command line are shown. By pressing Alt-up and Alt-down, a history search is also performed, but instead of searching for a complete commandline, each commandline is tokenized into separate elements just like it would be before execution, and each such token is matched agains the token under the cursor when the search began. History searches can be aborted by pressing the escape key. The history is stored in the file '.fish_history'. It is automatically read on startup and merged on program exit. Example: To search for previous entries containing the word 'make', type 'make' in the console and press the up key. \section job-control Running multiple programs Normally when \c fish starts a program, this program will be put in the foreground, meaning it will take control of the terminal and \c fish will be stopped until the program finishes. Sometimes this is not desirable. For example, you may wish to start an application with a graphical user interface from the terminal, and then be able to continue using the shell. In such cases, there are several ways in which the user can change fish's behaviour. -# By ending a command with the \& (ampersand) symbol, the user tells \c fish to put the specified command into the background. A background process will be run simultaneous with \c fish. \c fish will retain control of the terminal, so the program will not be able to read from the keyboard. -# By pressing ^Z, the user stops a currently running foreground program and returns control to \c fish. Some programs do not support this feature, or remap it to another key. Gnu emacs uses ^X z to stop running. -# By using the fg and bg builtin commands, the user can send any currently running job into the foreground or background. \section initialization Initialization files On startup, \c fish evaluates the file /etc/fish (Or ~/etc/fish if you installed fish in your home directory) and ~/.fish, in that order. If you want to run a command only on starting an interactive shell, use the exit status of the command 'status --is-interactive' to determine if the shell is interactive. If you want to run a command only on starting a login shell, use 'status --is-login' instead. Example: If you want to add the directory ~/linux/bin to your PATH variable when loging in, add the following to your ~/.fish file: 
if status --is-login
	set PATH $PATH ~/linux/bin
end
If you want to run a set of commands when \c fish exits, use an event handler that is triggered by the exit of the shell: 
function on_exit --on-process %self
	echo fish is now exiting
end
Universal variables are stored in the file .fishd.HOSTNAME, where HOSTNAME is the name of your computer. Do not edit this file directly, edit them through fish scripts or by using fish interactively instead. \section other Other features \subsection color Syntax highlighting \c fish interprets the command line as it is typed and uses syntax highlighting to provide feedback to the user. The most important feedback is the detection of potential errors. By default, errors are marked red. Detected errors include: - Non existing commands. - Reading from or appending to a non existing file. - Incorrect use of output redirects - Mismatched parenthesis When the cursor is over a parenthesis or a quote, \c fish also highlights it's matching quote or parenthesis. To customize the syntax highlighting, you can set the environment variables \c fish_color_normal, \c fish_color_command, \c fish_color_substitution, \c fish_color_redirection, \c fish_color_end, \c fish_color_error, \c fish_color_param, \c fish_color_comment, \c fish_color_match, \c fish_color_search_match, \c fish_color_cwd, \c fish_pager_color_prefix, \c fish_pager_color_completion, \c fish_pager_color_description and \c fish_pager_color_progress. Usually, the value of these variables will be one of \c black, \c red, \c green, \c brown, \c yellow, \c blue, \c magenta, \c purple, \c cyan, \c white or \c normal, but they can be an array containing any color options for the set_color command. Issuing set fish_color_error black --background=red --bold will make all commandline errors be written in a black, bold font, with a red background. \subsection prompt Programmable prompt By defining the \c fish_prompt function, the user can choose a custom prompt. The \c fish_prompt function is executed and the output is used as a prompt. Example:

The default \c fish prompt is 

function fish_prompt -d "Write out the prompt"
	printf '\%s\@\%s\%s\%s\%s> ' (whoami) (hostname|cut -d . -f 1) (set_color \$fish_color_cwd) (prompt_pwd) (set_color normal)
end
where \c prompt_pwd is a shellscript function that displays a condensed version of the current working direcotry.

\subsection title Programmable title When running in a virtual terminal, the user define the \c fish_title function to print a custom titlebar message. The \c fish_title function is executed and the output is used as a titlebar message. Example:

The default \c fish title is 

function fish_title
	echo $_ ' '
	pwd
end

\subsection event Event handlers When defining a new function in fish, it is possible to make it into an event handler, i.e. a function that is automatically run when a specific event takes place. Events that can trigger a handler currently are: * When a signal is delivered * When a process or job exits * When the value of a variable is updated Example: To specify a signal handler for the WINCH signal, write: 
function --on-signal WINCH my_signal_handler
	echo Got WINCH signal!
end
For more information on how to define new event handlers, see the documentation for the function command. \section issues Common issues with fish If you install fish in your home directory, fish will not work correctly for any other user than yourself. This is because fish needs it's initalization files to function properly. To solve this problem, either copy the initialization files to each fish users home directory, or install them in /etc. \section i18n Translating fish to other languages Fish uses the GNU gettext library to implement translation to multiple languages. If fish is not available in your language, please consider making a translation. Currently, only the shell itself can be translated, a future version of fish should also include translated manuals. To make a translation of fish, you will first need the sourcecode, available from the fish homepage. Download the latest version, and then extract it using a command like tar -zxf fish-VERSION.tar.gz. Next, cd into the newly created fish directory using cd fish-VERSION. You will now need to configure the sourcecode using the command ./configure. This step might take a while. Before you continue, you will need to know the ISO 639 language code of the language you are translating to. These codes can be found here. For example, the language code for Uighur is ug. Now you have the sourcecode and it is properly configured. Lets start translating. To do this, first create an empty translation table for the language you wish to translate to by writing make po/[LANGUAGE CODE].po in the fish terminal. For example, if you are translating to Uighur, you should write make po/ug.po. This should create the file po/ug.po, a template translation table containing all the strings that need to be translated. Now you are all set up to translate fish to a new language. Open the newly created .po file in your editor of choice, and start translating. The .po file format is rather simple. It contains pairs of string in a format like: 
msgid "%ls: No suitable job\n"
msgstr ""
The first line is the english string to translate, the second line should contain your translation. For example, in swedish the above might become: 
msgid "%ls: No suitable job\n"
msgstr "%ls: Inget jobb matchar\n"
\%s, \%ls, %\d and other tokens beginning with a '\%' are placeholders. These will be replaced by a value by fish at runtime. You must always take care to use exactly the same placeholders in the same order in your translation. (Actually, there are ways to avoid this, but they are to complicated for this short introduction. See the full manual for the printf C function for more information.) Once you have provided a translation for fish, please send it to fish-users@lists.sf.net. \section todo Missing features and bugs \subsection todo-features Missing features - Complete vi-mode key bindings - next-history-complete - More completions (for example xterm, vim, konsole, gnome-terminal, dcop, cdrecord, cron, xargs rlogin, telnet, rsync, arch, finger, nice, locate, bibtex, patch, aspell, xpdf, compress, wine, xmms, dig, wine, batch, cron, g++, javac, java, gcj, lpr, doxygen, whois, find) - Undo support - Check keybinding commands for output - if nothing has happened, don't repaint to reduce flicker - The jobs builtin should be able to give information on a specific job, such as the pids of the processes in the job - Syntax highlighting should mark cd to non-existing directories as an error - wait shellscript - Signal handler to save the history file before exiting from a signal \subsection todo-possible Possible features - Multiline editing - tab completion could use smart casing - Completions could support options beginning with a plus (like xterm +fbx) and options without dashes (like top p) Do we really want to complicate the code additionally for such a small number of programs? - mouse support like zsh has with http://stchaz.free.fr/mouse.zsh installed would be awesome - suggest a completion on unique matches by writing it out in an understated color - With a bit of tweakage, quite a few of the readline key-binding functions could be implemented in shellscript. - Highlight beginning/end of block when moving over a block command - Inclusion guards for the init files to make them evaluate only once, even if the user has installed fish both in /etc and in $HOME - Do not actually load most of the shellscript functions on startup. Only load a tiny wrapper that will load the real function when needed. This should shave of CPU-time spent on parsing 500-1000 lines of code and ~50 kB of memory on startup, and is pretty easy to implement. - Do not actually load/parse .fish_history, only mmap it and use some clever string handling. Should save ~150 kB of memory permanently, but is very hard to implement. - command specific wildcarding (use case * instead of case '*', etc.) - show the whole list of commands on using tab on an empty commandline - Automatically move cursor to the end of the current token before completing - Map variables. (export only the values. When expanding with no key specified, expand to all values.) - Descriptions for variables using 'set -d'. - Parse errors should when possible honor IO redirections \subsection bugs Known bugs - Completion for gcc -\#\#\# option doesn't work. - Yanking weird characters from clipboard prints Unicode escapes - Suspending and then resuming pipelines containing a builtin is broken. How should this be handled? If you think you have found a bug not described here, please send a report to axel@liljencrantz.se . \subsection issues Known issues Older versions of Doxygen has bugs in the man-page generation which cause the builtin help to render incorrectly. Version 1.2.14 is known to have this problem. In version 1.9.2, the installation prefix for fish rpms and debs changed from /usr/local to /usr. Packages should automatically change any instances of /usr/local/bin/fish in /etc/passwd to /usr/bin/fish, but some programs, like screen, may need to be restarted to notice the changes when upgrading from pre1.9.2 to 1.9.2 or later. You may also run into such problems when switching between using a package and personal builds. */ /** \page design Design document \section design-overview Design document \subsection design-overview Overview This is a description of the design principles that have been used to design fish. The fish design has three high level goals. These are: -# Everything that can be done in other shell languages should be possible to do in fish, though fish may rely on external commands in doing so. -# Fish should be user friendly, but not at the expense of expressiveness. Most tradeoffs between power and ease of use can be avoided with careful design. -# Whenever possible without breaking the above goals, fish should follow the Posix syntax. To achive these high-level goals, the fish design relies on a number of more specific design principles. These are presented below, together with a rationale and a few examples for each. \subsection ortho The law of orthogonality The shell language should have a small set of orthogonal features. Any situation where two features are related but not identical, one of them should be removed, and the other should be made powerful and general enough to handle all common use cases of either feature. Rationale: Related features make the language larger, which makes it harder to learn. It also increases the size of the sourcecode, making the program harder to maintain and update. Examples: - Here documents are too similar to using echo inside of a pipeline. - Subshells, command substitution and process substitution are strongly related. \c fish only supports command substitution, the others can be achived either using a block or the psub shellscript function. - Having both aliases and functions is confusing, especially since both of them have limitations and problems. \c fish sunctions have none of the drawbacks of either syntax. - The many Posix quoting styles are silly, especially \$''. \subsection sep The law of minimalism The shell should only contain features that cannot be implemented in a reasonable way outside of the shell. A large performance decrease, as well as some program complexity increase is acceptable in order to improve separation. Rationale: A modular project is easier to maintain since smaller programs are far easier to understand than larger ones. A modular project is also more future proof since the modules can be individually replaced. Modularity also decreases the severity of bugs, since there is good hope that a bug, even a serious one, in one module, does not take the whole system down. Examples: - Builtin commands should only be created when it cannot be avoided. \c echo, \c kill, \c printf and \c time are among the commands that fish does not implement internally since they can be provided as external commands. Several other commands that are commonly implemented as builtins and can not be implemented as external commands, including \c type, \c vared, \c pushd and \c popd are implemented as shellscript functions in fish. - Mathematical calculations, regex matching, generating lists of numbers and many other funtions can easily be done in external programs. They should not be supported internally by the shell. The law of minimalism does not imply that a large feature set is bad. So long as a feature is not part of the shell itself, but a separate command or at least a shellscript function, bloat is fine. \subsection conf Configurability is the root of all evil Every configuration option in a program is a place where the program is too stupid to figure out for itself what the user really wants, and should be considered a failiure of both the program and the programmer who implemented it. Rationale: Different configuration options are a nightmare to maintain, since the number of potential bugs caused by specific configuration combinations quickly becomes an issue. Configuration options often imply assumptions about the code which change when reimplementing the code, causing issues with backwards compatibility. But mostly, configuration options should be avoided since they simply should not exist, as the program should be smart enough to do what is best, or at least a good enough approximation of it. Examples: - Fish allows the user to set various syntax highlighting colors. This is needed because fish does not know what colors the terminal uses by default, which might make some things unreadable. The proper solution would be for text color preferences to be defined centrally by the user for all programs, and for the terminal emulator to send these color properties to fish. - Fish does not allow you to set the history filename, the number of history entries, different language substyles or any number of other common shell configuration options. A special note on the evils of configurability is the long list of very useful features found in some shells, that are not turned on by default. Both zsh and bash support command specific completions, but no such completions are shipped with bash by default, and they are turned of by default in zsh. Other features that zsh support that are disabled by default include tab-completion of strings containing wildcards, a sane completion pager and a history file. \subsection user The law of user focus When designing a program, one should first think about how to make a intuitive and powerful program. Implementation issues should only be considered once a user interface has been designed. Rationale: This design rule is different than the others, since it describes how one should go about designing new features, not what the features should be. The problem with focusing on what can be done, and what is easy to do, is that to much of the implementation is exposed. This means that the user must know a great deal about the underlying system to be able to guess how the shell works, it also means that the language will often be rather low-level. Examples: - There should only be one type of input to the shell, lists of commands. Loops, conditionals and variable assignments are all performed through regular commands. - The differences between builtin commands, shellscript functions and builtin commands should be made as small as possible. Builtins and shellscript functions should have exactly the same types of argument expansion as other commands, should be possible to use in any position in a pipeline, and should support any io redirection. - Instead of forking when performing command substitution to provide a fake variable scope, all fish commands are performed from the same process, and fish instead supports true scoping - All blocks end with the \c end builtin \subsection disc The law of discoverability The shell should implement it's features in a way that makes them as easy as possible for the user to discover for her/himself. Rationale: A program whose features are discoverable makes a new user into an expert in a shorter span of time, since the user will learn how to use the program simply by using it. The main benefit of a graphical program over a command line-based program is discoverability. In a graphical program, one can discover all the common features by simply looking at the user interface and guessing what the different buttons, menus and other widgets do. The traditional way to discover features in commandline programs is through manual pages. This requires both that the user starts to use a different program, and the she/he then remembers the new information until the next time she/he uses the same program. Examples: - Everything should be tab-completable, and every tab completion should have a description - Every syntax error and error in a builtin command should contain an error message describing what went wrong and a relevant help page. Whenever possible, errors should be flagged red by the syntax highlighter. - The help manual should be easy to read, easily available from the shell, complete and contain many examples - The language should be uniform, so that once the user understands the command/argument syntax, he will know the whole language, and be able to use tab-completion to discover new featues. */ /** \page about About fish \section about-program About the program \c fish is meant to be used for interactive shell tasks on a modern UNIX-like workstation. It is much more important for me to keep the code maintainable, readable and bug free than to support esoteric old hardware, software or wetware. As such, the program is often wildly inefficient in its use of memory and CPU cycles. On my system, \c fish uses a little less than half a megabyte of memory, a number that could be significantly reduced with a little effort. \c fish performs a lot of linear searches of things that could be done in logarithmic time, does not usually cache file system data or other search result, and uses the fork() call promiscuosly. None of these things matter because \c fish is still fast enough to be perceived as instantaneous on a semi-modern computer thanks to the miracles of copy-on-write, OS-level caching and Moores law, and it only uses a fraction of the memory used by most terminal emulators to display it. If this program was anything other than an amusing hobby for me, I would of course feel otherwise, but since my time is limited, this is the way it must be. \section about-code About the source code Fish is written using the ellemtel indentation style, using four space tabs. \c fish regularly performs a large set of sanity checks to make sure it is in a sane state. If not, the program will terminate before it can do any harm. Do not edit the file builtin_help.c, it is automatically generated. \section about-documentation About the documentation The documentation for \c fish is written for Doxygen. All header files are pretty heavily commented. Since it was desirable to use the same text files for producing the HTML documentation as for producing the internal help output, some rather ugly kludges had to be used for writing the documentation for the builtin commands. The directory doc_src contains a file called doc.hdr, containing various general documentation for \c fish, and a large number of .txt files. Each txt file contains the documentation for one \c fish builtin. When creating the main doxygen documentation, all these files are concatenated into one file, called doc.h. When creating the internal documentation, each of the .txt files is converted to a .h file by supplying a doxygen header/footer. These headers are then converted into man style manuals, which in turn are converted to C code by a script called gen_hdr.sh. The resulting C-file, builtin_help.c, can then by linked into \c fish. This method is probably not the most robust, elegant or clever method for generating documentation. If someone has a suggestion of how to do i better, please notify me. */ /** \page difference Why fish? \section difference-overview What is different about fish? This page is a summary of differences between \c fish and other shells. \subsection difference-completion Tab completion features \c fish, like many other shells, performs tab completion, i.e. the shell tries to guess what the user is typing and complete the users sentences whenever the user presses the tab key. If the shell finds more than one possible completion, a list of all completions is displayed when the users double taps on tab. \c fish extends tab completion functionality in several ways: - \c fish performs file completion on strings containing wildcards - When showing a list of possible completions, \c fish adds a description to each completion. For files this description is a description of the format or filetype, like 'C source code', 'Character device' or 'Executable'. For variables, if the value is short enough, the variable value will be displayed. For commands, if there is room and few enough commands, the whatis description of the command is used. - \c fish has extensive command specific completions, including completion of specific options. This is very powerful in combination with completion descriptions, as the user can see what each option does without consulting the manual. Simply type the command you wish to use, type a dash and double tab TAB, and the screen will fill with a list of the commands options and a description of what they do. - \c fish uses a decent pager when the results won't fit on one screen. The pager can scroll up and down, both one row and one page at a time, and if any non movement key is pressed the pager exits without consuming the character. Therefore, there is no need to press 'q' to exit before typing your completion. Some examples of the completions performed by \c fish - When completing an argument for the man command, the whatis database is searched for manual pages as completions. - When completing a command name, the whatis database is searched for each possible command, and the description returned is used as the description of the command. - When completing an argument for the make command, the Makefile in the current directory is searched for targets. \subsection difference-killring X-Windows Copy and paste \c fish supports using the X-Windows clipboard for storing copy and paste information. This feature is automatically enabled if the DISPLAY environment variable is set. For more information on how to use copy and paste in \c fish, read this section. This means you can easily share commands and strings between different shell sessions and applications. \subsection difference-open Simple launching of default applications The open command uses the mimetype database (Also used by both Gnome or KDE) to launch the default application for a file. Just type open *.html and all the HTML files in your current directory will be opened in your default browser. No longer will you have to convert your filenames to URLS, remember clunky Open Office command names, worry about absolute paths or any the other common pitfalls when opening files from the commandline. \subsection difference-help Help \c fish is heavily commented. Both the source code and the program in general features a great deal of easily accessible documentation. The help command is used to display HTML-based help files. Just type help and a subject, and the help system will try to fill your needs. To view the page you are reading right now, you could simply type help difference. help also works great together with tab completion. Write \c help and double tap on tab, a list of all help sections will be displayed, with a description of the content of each section. Also, all builtin commands have a help option. Passing '-h' or '--help' to any builtin will give you the same help as the help command, but formated for output on screen. \subsection difference-highlighting Syntax highlighting \c fish performs syntax highlighting of commands as they're entered. Pretty colors may look nice (or awful, depending on your taste), but the real advantage is error flagging. The syntax highlighting function does extensive error cheching and will flag many common errors such as misspelling a command or option, or reading from a non-existent file. \c fish also highlights matching quotes and parenthesis as the cursor moves over them. This is very useful when typing long, complex commands. \subsection difference-terminal Terminal handling \c fish knows it's terminal. \c fish uses the terminfo database to get more information on the current terminal. Some of the terminal handling features of \c fish are: - Backspace and delete work more often in \c fish thanks to the use of terminfo. If you've been bitten by this, you'll know what this means. - If the screen has been written to when \c fish was in the foreground, this is detected and the command line is redrawn. - Process notifications, like jobs ending or being stopped by signals, are printed to the screen at once, not whenever the user presses the enter key. \c fish uses wide character strings internally, including double width characters, so it should be ready for all your Unicode needs. \subsection difference-history Smart history \c fish features an intelligent history that automatically removes any duplicate items. Searching is performed by entering a search string and using the up/down arrow keys to go to the next/previous match. On exit, \c fish performs a merge between the history on file and the history in memory history, thus making sure that multiple copies of \c fish running concurrently will not erase each others history information. \subsection difference-simple Simplicity \c fish has a simple syntax. There is only one form of alias/function/whatever, accessed through the function builtin. The are very few builtins, \c fish relies on normal commands like echo, kill, printf and time instead of reimplementing them as builtins. Token separation is performed before variable expansion. This means that even if a variable contains spaces, it will never be separated into multiple arguments. If you want to tokenize a string, you can use the tokenize command. Command substitution is specified using parenthesis, as in set name (whoami). There is no math mode, use bc. The POSIX way of setting variables is lame. Whitespace sensitive languages are awful. "foo=bar" and "foo = bar" should not mean different things. \c fish uses a builtin, set to set and remove environment variables. While this may seem a bit obscure, this makes for a very consistent language. In fish, everything, including the loops, assignments and switch/case statements is a command. In \c fish, all block types end with the \c end command. */ /** \page license License \c fish Copyright (C) 2005 Axel Liljencrantz. It is released under the GNU General Public License. The license agreement is included below. For more information on the GNU project and its goals, visit the GNU homepage. \c fish also contains small amounts of code under the BSD license, namely versions of the two functions strlcat and strlcpy, modified for use with wide character strings. This code is copyrighted by Todd C. Miller. The XSel command, written and copyrighted by Conrad Parker, is distributed together with \c fish. It is released under the MIT license. The xdgmime library, written and copyrighted by Red Hat, Inc, is used by the mimedb command, which is a part of fish. It is released under the LGPL license.

GNU GENERAL PUBLIC LICENSE

Version 2, June 1991 

Copyright (C) 1989, 1991 Free Software Foundation, Inc.  
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

Preamble

The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.

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Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.

The precise terms and conditions for copying, distribution and modification follow.

TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.

1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.

You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.

2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:

a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.

b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.

c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)

These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.

In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.

3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:

a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)

The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code.

4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.

6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.

7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances.

It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice.

This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.

8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License.

9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.

10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally.

NO WARRANTY

11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. 

one line to give the program's name and an idea of what it does.
Copyright (C) yyyy  name of author

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this when it starts in an interactive mode: 

Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.  This is free software, and you are welcome
to redistribute it under certain conditions; type `show c' 
for details.

The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: 

Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written 
by James Hacker.

signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice

This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License.

License for wcslcat and wcslcpy

\c fish also contains small amounts of code under the BSD license, namely versions of the two functions strlcat and strlcpy, modified for use with wide character strings. This code is copyrighted by Todd C. Miller. Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

License for XSel

The XSel command, written and copyrighted by Conrad Parker, is distributed together with \c fish. It is Copyright (C) 2001 Conrad Parker Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. No representations are made about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. */