How to Redirect Stderr and Stdout to Different Files in the Same Line in Script

How to redirect stderr and stdout to different files in the same line in script?

Just add them in one line command 2>> error 1>> output

However, note that >> is for appending if the file already has data. Whereas, > will overwrite any existing data in the file.

So, command 2> error 1> output if you do not want to append.

Just for completion's sake, you can write 1> as just > since the default file descriptor is the output. so 1> and > is the same thing.

So, command 2> error 1> output becomes, command 2> error > output

How to redirect and append both standard output and standard error to a file with Bash

cmd >>file.txt 2>&1

Bash executes the redirects from left to right as follows:

1. >>file.txt: Open file.txt in append mode and redirect stdout there.
2. 2>&1: Redirect stderr to "where stdout is currently going". In this case, that is a file opened in append mode. In other words, the &1 reuses the file descriptor which stdout currently uses.

How to redirect both stdout and stderr to a file

If you want to log to the same file:

command1 >> log_file 2>&1

If you want different files:

command1 >> log_file 2>> err_file

redirect stdout and stderr to one file, copy of just stderr to another

You can use an additional file descriptor and tee:

{ foo.sh 2>&1 1>&3- | tee stderr.txt; } > stdout_and_stderr.txt 3>&1

Be aware that line buffering may cause the stdout output to appear out of order. If this is a problem, there are ways to overcome that including the use of unbuffer.

How to redirect stderr and stdout to different files in the same line in script?

Just add them in one line command 2>> error 1>> output

However, note that >> is for appending if the file already has data. Whereas, > will overwrite any existing data in the file.

So, command 2> error 1> output if you do not want to append.

Just for completion's sake, you can write 1> as just > since the default file descriptor is the output. so 1> and > is the same thing.

So, command 2> error 1> output becomes, command 2> error > output

How to redirect stderr and stdout to more than one output file?

you can do it with tee command in combination of process substitution.

#!/bin/bash

exec 3> all.txt # fd3 goes to all.txt
exec 1> >(tee output.txt >&3) # fd1(stdout) goes to both output.txt and fd3
exec 2> >(tee error.txt >&3) # fd2(stderr) goes to both error.txt and fd3

echo Go To Stdout # goes to fd1, and fd1 goes to both output.txt and fd3 (which goes to all.txt)
echo Go To Stderr >&2 # goes to fd2, and fd2 goes to both error.txt and fd3 (which goes to all.txt)

Redirect stdout and stderr to a file and also to console in linux

The tee command can help you out. It reads from standard input and writes to standard output and files.

So the following command will do:

some_command.sh 2>&1 | tee file.txt

Manpage: http://man7.org/linux/man-pages/man1/tee.1.html

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