Make 'entr' execute a locally defined shell function

reno_rita

entr is used to run shell commands when files change. The following script will output File changed. whenever the file /tmp/data.txt is modified. #!/usr/bin/env sh echo "/tmp/data.txt" | entr -s 'echo "File changed."' Once the commands to execute become more complex it would be convenient to move them to a separate function and make entr call the function, like so: #!/usr/bin/env sh foo() { echo "File changed!"; } echo "$0" | entr -s 'foo' #...

Originally asked by korolev on Stack Exchange (unix) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

You should export SHELL=/bin/bash before invoking entr -s cmd if you want to be able to use bash exported functions inside cmd . As documented in the manpage of entr (emphasis mine): -s Evaluate the first argument using the interpreter specified by the SHELL environment variable . Not necessarily /bin/bash , the shell it was called from, or the login shell of the user. If SHELL is not defined (it doesn't have to, in a script, etc), then entr will set it itself to /bin/sh , which on Debian is dash , a shell which cannot use the functions exported by bash and, moreover, will remove them from the environment.

Full answer by user313992: https://unix.stackexchange.com/a/573030 (CC BY-SA 4.0).

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