Read values into a shell variable from a pipe

by

Use

IFS= read var << EOF
$(foo)
EOF

You can trick read into accepting from a pipe like this:

echo "hello world" | { read test; echo test=$test; }

or even write a function like this:

read_from_pipe() { read "$@" <&0; }

But there’s no point – your variable assignments may not last! A pipeline may spawn a subshell, where the environment is inherited by value, not by reference. This is why read doesn’t bother with input from a pipe – it’s undefined.

FYI, http://www.etalabs.net/sh_tricks.html is a nifty collection of the cruft necessary to fight the oddities and incompatibilities of bourne shells, sh.

More Related Contents:

  1. Pipe output to bash function
  2. Is it OK to use the same input file as output of a piped command?
  3. Pass a password to ssh in pure bash
  4. Example of using named pipes in Linux shell (Bash)
  5. pass stdout as file name for command line util?
  6. How to read a file line by line and making a new file for each line having same filename as last word of each line? [closed]
  7. How to permanently set $PATH on Linux/Unix [closed]
  8. How do I use sudo to redirect output to a location I don’t have permission to write to? [closed]
  9. How to get overall CPU usage (e.g. 57%) on Linux [closed]
  10. cronjob does not execute a script that works fine standalone
  11. How to escape single quotes in Bash/Grep?
  12. What does `set -x` do?
  13. “find: paths must precede expression:” How do I specify a recursive search that also finds files in the current directory?
  14. Does “argument list too long” restriction apply to shell builtins?
  15. Given two directory trees, how can I find out which files differ by content? [closed]
  16. bash alias command with both single and double quotes
  17. Take nth column in a text file
  18. How to remove non UTF-8 characters from text file
  19. Uppercasing First Letter of Words Using SED
  20. Find the files that have been changed in last 24 hours
  21. Tar a directory, but don’t store full absolute paths in the archive
  22. Get last dirname/filename in a file path argument in Bash
  23. bash command not found when setting a variable
  24. How to obtain the number of CPUs/cores in Linux from the command line?
  25. Exit code of variable assignment to command substitution in Bash
  26. Move all files except one
  27. Using `date` command to get previous, current and next month
  28. Run script with rc.local: script works, but not at boot
  29. Write a bash shell script that consumes a constant amount of RAM for a user defined time [closed]
  30. Using “$RANDOM” to generate a random string in Bash

Leave a Comment