How do you redirect the output of a command to a variable in Linux?
To store the output of a command in a variable, you can use the shell command substitution feature in the forms below: variable_name=$(command) variable_name=$(command [option …] arg1 arg2 …) OR variable_name=’command’ variable_name=’command [option …] arg1 arg2 …’
How do I capture stderr?
To redirect stderr as well, you have a few choices:
- Redirect stdout to one file and stderr to another file: command > out 2>error.
- Redirect stdout to a file ( >out ), and then redirect stderr to stdout ( 2>&1 ): command >out 2>&1.
How to catch stdout and stderr in different variables?
Tested on Debian wheezy using GNU bash, Version 4.2.37 (1)-release (i486-pc-linux-gnu). This is for catching stdout and stderr in different variables. If you only want to catch stderr, leaving stdout as-is, there is a better and shorter solution.
How to capture stdout and stderr in Bash?
Next, the stdout of out is assigned to y, and the redirected stderr is captured by x, without the usual loss of y to a command substitution’s subshell. It isn’t possible in other shells, because all constructs which capture output require putting the producer into a subshell, which in this case, would include the assignment.
How to catch a typo in Bash-X?
Q: There is a typo. : catch STDOUT STDERR cmd args.. shall read # catch STDOUT STDERR cmd args.. Actually this is intended. : shows up in bash -x while comments are silently swallowed. So you can see where the parser is if you happen to have a typo in the function definition.
Can a shell variable be changed in Bash?
Shell-variables cannot carry the byte NUL ( $’\\0′ ). They are simply ignores if they happen to occur in stdout or stderr. The given command runs in a sub-subshell. So it has no access to $PPID, nor can it alter shell variables.