I know that in Linux, to redirect output from the screen to a file, I can either use the > or tee. However, I'm not sure why part of the output is still output to the screen and not written to the file.
Is there a way to redirect all output to file?
That part is written to stderr, use 2> to redirect it. For example:
foo > stdout.txt 2> stderr.txt
or if you want in same file:
foo > allout.txt 2>&1
Note: this works in (ba)sh, check your shell for proper syntax
cmd1 2>&1 | cmd2; putting the 2>&1 after the | will redirect stderr for cmd2 instead. If both stdout and stderr are redirected, a program can still access the terminal (if any) by opening /dev/tty; this is normally done only for password prompts (e.g. by ssh). If you need to redirect that too, the shell cannot help you, but expect can.
> to >> to append instead of overwrite. Kinda obvious but worth mentioning.
foo >> allout.txt 2>>&1 or foo >> allout.txt 2>&1?All POSIX operating systems have 3 streams: stdin, stdout, and stderr. stdin is the input, which can accept the stdout or stderr. stdout is the primary output, which is redirected with >, >>, or |. stderr is the error output, which is handled separately so that any exceptions do not get passed to a command or written to a file that it might break; normally, this is sent to a log of some kind, or dumped directly, even when the stdout is redirected. To redirect both to the same place, use:
$command &> /some/file
EDIT: thanks to Zack for pointing out that the above solution is not portable--use instead:
$command > file 2>&1
If you want to silence the error, do:
$command 2> /dev/null
&> file (aka >& file) is not part of the official POSIX shell spec, but has been added to many Bourne shells as a convenience extension (it originally comes from csh). In a portable shell script (and if you don't need portability, why are you writing a shell script?), use > file 2>&1 only.
To get the output on the console AND in a file file.txt for example.
make 2>&1 | tee file.txt
Note: & (in 2>&1) specifies that 1 is not a file name but a file descriptor.
Use this - "require command here" > log_file_name 2>&1
Detail description of redirection operator in Unix/Linux.
The > operator redirects the output usually to a file but it can be to a device. You can also use >> to append.
If you don't specify a number then the standard output stream is assumed but you can also redirect errors
> file redirects stdout to file
1> file redirects stdout to file
2> file redirects stderr to file
&> file redirects stdout and stderr to file
/dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output.
&> is an extension supported by some shells, but not specified by POSIX. Be prepared for it to break in #!/bin/sh scripts if dash is your /bin/sh. In dash, it parses the same as two separate commands: foo &, i.e. running the command in the background with output connected to the shell's stdout (e.g. the terminal), and then separately >output which truncates the output file. The other ones are standard syntax, and all of them work in Bash and Zsh, and other typical interactive shells that modern GNU/Linux distros provide as their default.Credits to osexp2003 and j.a. …
Instead of putting:
&>> your_file.log
behind a line in:
crontab -e
I use:
#!/bin/bash
exec &>> your_file.log
…
at the beginning of a BASH script.
Advantage: You have the log definitions within your script. Good for Git etc.
&>> /dev/null only works with BASH and redirects both STANDARD_OUT (1) and STANDARD_ERROR (2) to Nirvana (3 is STANDARD_IN). In this particular case, it makes no difference whether you overwrite (&>) or append (&>>).You can use exec command to redirect all stdout/stderr output of any commands later.
sample script:
exec 2> your_file2 > your_file1
your other commands.....
It might be the standard error. You can redirect it:
... > out.txt 2>&1
Use >> to append:
command >> file
