Capture stdout and stderr into different variables

by

Ok, it got a bit ugly, but here is a solution:

unset t_std t_err
eval "$( (echo std; echo err >&2) \
        2> >(readarray -t t_err; typeset -p t_err) \
         > >(readarray -t t_std; typeset -p t_std) )"

where (echo std; echo err >&2) needs to be replaced by the actual command. Output of stdout is saved into the array $t_std line by line omitting the newlines (the -t) and stderr into $t_err.

If you don’t like arrays you can do

unset t_std t_err
eval "$( (echo std; echo err >&2 ) \
        2> >(t_err=$(cat); typeset -p t_err) \
         > >(t_std=$(cat); typeset -p t_std) )"

which pretty much mimics the behavior of var=$(cmd) except for the value of $? which takes us to the last modification:

unset t_std t_err t_ret
eval "$( (echo std; echo err >&2; exit 2 ) \
        2> >(t_err=$(cat); typeset -p t_err) \
         > >(t_std=$(cat); typeset -p t_std); t_ret=$?; typeset -p t_ret )"

Here $? is preserved into $t_ret

Tested on Debian wheezy using GNU bash, Version 4.2.37(1)-release (i486-pc-linux-gnu).

More Related Contents:

  1. How do I set a variable to the output of a command in Bash?
  2. Why do you need ./ (dot-slash) before executable or script name to run it in bash?
  3. Redirect stderr and stdout in Bash [duplicate]
  4. What is the purpose of “&&” in a shell command?
  5. Shell redirection i/o order
  6. How to reload .bash_profile from the command line
  7. Why do I get “/bin/sh: Argument list too long” when passing quoted arguments?
  8. pipe stdout and stderr to two different processes in shell script?
  9. Convert line endings [duplicate]
  10. Why doesn’t my terminal output unicode characters properly?
  11. Command not found error in Bash variable assignment
  12. How to check if a variable is set in Bash
  13. What is the difference between $(command) and `command` in shell programming?
  14. Can I export a variable to the environment from a Bash script without sourcing it?
  15. How to urlencode data for curl command?
  16. Shell equality operators (=, ==, -eq)
  17. Assigning default values to shell variables with a single command in bash
  18. redirect COPY of stdout to log file from within bash script itself
  19. Shell script to delete directories older than n days
  20. How to echo shell commands as they are executed
  21. Random number from a range in a Bash Script
  22. How to check the exit status using an ‘if’ statement
  23. Longest line in a file
  24. How to write a bash script to set global environment variable?
  25. What does “plus colon” (“+:”) mean in shell script expressions?
  26. Running shell command that has nested quotes via ssh
  27. Floating point comparison in shell
  28. Escaping forward slashes in sed command [duplicate]
  29. run bash command in new shell and stay in new shell after this command executes
  30. How to read variables from file, with multiple variables per line?

Leave a Comment