Add --log-file flag to log everything (including panics) to file

README.md

@@ -125,15 +125,17 @@ the same format as the standard md5sum tool produces.
 General options:
 
 ```
-      --bwlimit=0: Bandwidth limit in kBytes/s, or use suffix k|M|G
+      --bwlimit=0: Bandwidth limit in kBytes/s, or use suffix K|M|G
       --checkers=8: Number of checkers to run in parallel.
       --config="~/.rclone.conf": Config file.
   -n, --dry-run=false: Do a trial run with no permanent changes
+      --log-file="": Log everything to this file
       --modify-window=1ns: Max time diff to be considered the same
   -q, --quiet=false: Print as little stuff as possible
-      --stats=1m0s: Interval to print stats
+      --stats=1m0s: Interval to print stats (0 to disable)
       --transfers=4: Number of file transfers to run in parallel.
   -v, --verbose=false: Print lots more stuff
+  -V, --version=false: Print the version number
 ```
 
 Developer options:

docs/content/docs.md

@@ -107,15 +107,17 @@ the same format as the standard md5sum tool produces.
 General options:
 
 ```
-      --bwlimit=0: Bandwidth limit in kBytes/s, or use suffix k|M|G
+      --bwlimit=0: Bandwidth limit in kBytes/s, or use suffix K|M|G
       --checkers=8: Number of checkers to run in parallel.
-      --transfers=4: Number of file transfers to run in parallel.
       --config="~/.rclone.conf": Config file.
   -n, --dry-run=false: Do a trial run with no permanent changes
+      --log-file="": Log everything to this file
       --modify-window=1ns: Max time diff to be considered the same
   -q, --quiet=false: Print as little stuff as possible
-      --stats=1m0s: Interval to print stats
+      --stats=1m0s: Interval to print stats (0 to disable)
+      --transfers=4: Number of file transfers to run in parallel.
   -v, --verbose=false: Print lots more stuff
+  -V, --version=false: Print the version number
 ```
 
 Developer options:

rclone.go

@@ -30,6 +30,7 @@ var (
 	cpuprofile    = pflag.StringP("cpuprofile", "", "", "Write cpu profile to file")
 	statsInterval = pflag.DurationP("stats", "", time.Minute*1, "Interval to print stats (0 to disable)")
 	version       = pflag.BoolP("version", "V", false, "Print the version number")
+	logFile       = pflag.StringP("log-file", "", "", "Log everything to this file")
 )
 
 type Command struct {
@@ -343,6 +344,17 @@ func main() {
 	}
 	command, args := ParseCommand()
 
+	// Log file output
+	if *logFile != "" {
+		f, err := os.OpenFile(*logFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
+		if err != nil {
+			log.Fatalf("Failed to open log file: %v", err)
+		}
+		f.Seek(0, os.SEEK_END)
+		log.SetOutput(f)
+		redirectStderr(f)
+	}
+
 	// Make source and destination fs
 	var fdst, fsrc fs.Fs
 	if len(args) >= 1 {

redirect_stderr.go

@@ -0,0 +1,15 @@
+// Log the panic to the log file - for oses which can't do this
+
+//+build !windows,!unix
+
+package main
+
+import (
+	"log"
+	"os"
+)
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	log.Printf("Can't redirect stderr to file")
+}

redirect_stderr_unix.go

@@ -0,0 +1,19 @@
+// Log the panic under unix to the log file
+
+//+build unix
+
+package main
+
+import (
+	"log"
+	"os"
+	"syscall"
+)
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	err := syscall.Dup2(int(f.Fd()), int(os.Stderr.Fd()))
+	if err != nil {
+		log.Fatalf("Failed to redirect stderr to file: %v", err)
+	}
+}

redirect_stderr_windows.go

@@ -0,0 +1,39 @@
+// Log the panic under windows to the log file
+//
+// Code from minix, via
+//
+// http://play.golang.org/p/kLtct7lSUg
+
+//+build windows
+
+package main
+
+import (
+	"log"
+	"os"
+	"syscall"
+)
+
+var (
+	kernel32         = syscall.MustLoadDLL("kernel32.dll")
+	procSetStdHandle = kernel32.MustFindProc("SetStdHandle")
+)
+
+func setStdHandle(stdhandle int32, handle syscall.Handle) error {
+	r0, _, e1 := syscall.Syscall(procSetStdHandle.Addr(), 2, uintptr(stdhandle), uintptr(handle), 0)
+	if r0 == 0 {
+		if e1 != 0 {
+			return error(e1)
+		}
+		return syscall.EINVAL
+	}
+	return nil
+}
+
+// redirectStderr to the file passed in
+func redirectStderr(f *os.File) {
+	err := setStdHandle(syscall.STD_ERROR_HANDLE, syscall.Handle(f.Fd()))
+	if err != nil {
+		log.Fatalf("Failed to redirect stderr to file: %v", err)
+	}
+}