fish-shell/share/functions/psub.fish

function psub --description "Read from stdin into a file and output the filename. Remove the file when the command that called psub exits."

    set -l dirname
    set -l filename
    set -l funcname
    set -l suffix
    set -l use_fifo 1

    while count $argv >/dev/null

        switch $argv[1]
            case -h --help
                __fish_print_help psub
                return 0

            case -f --file
                set use_fifo 0
                set -e argv[1]

            case -s --suffix
                if not set -q argv[2]
                    printf "psub: missing operand\n"
                    return 1
                end
                set suffix $argv[2]
                set -e argv[1..2]

            case --
                set -e argv[1]
                break

            case "-?" "--*"
                printf "psub: invalid option: '%s'\n" $argv[1]
                return 1

            case "-*"
                # Ungroup short options: -hfs => -h -f -s
                set opts "-"(string sub -s 2 -- $argv[1] | string split "")
                set -e argv[1]
                set argv $opts $argv

            case "*"
                printf "psub: extra operand: '%s'\n" $argv[1]
                return 1
        end
    end

    if not status --is-command-substitution
        echo psub: Not inside of command substitution >&2
        return 1
    end

    set -l tmpdir /tmp
    set -q TMPDIR
    and set tmpdir $TMPDIR

    if test use_fifo = 1
        # Write output to pipe. This needs to be done in the background so
        # that the command substitution exits without needing to wait for
        # all the commands to exit
        set dirname (mktemp -d $tmpdir/.psub.XXXXXXXXXX)
        or return
        set filename $dirname/psub.fifo"$suffix"
        mkfifo $filename
        cat >$filename &
    else if test -z $suffix
        set filename (mktemp $tmpdir/.psub.XXXXXXXXXX)
        cat >$filename
    else
        set dirname (mktemp -d $tmpdir/.psub.XXXXXXXXXX)
        set filename $dirname/psub"$suffix"
        cat >$filename
    end

    # Write filename to stdout
    echo $filename

    # Find unique function name
    while true
        set funcname __fish_psub_(random)

        if not functions $funcname >/dev/null ^/dev/null
            break

        end
    end

    # Make sure we erase file when caller exits
    function $funcname --on-job-exit caller --inherit-variable filename --inherit-variable dirname --inherit-variable funcname
        command rm $filename
        if count $dirname >/dev/null
            command rmdir $dirname
        end
        functions -e $funcname
    end

end