Yes, I know C-shell is bad. No, I did not choose C-shell. Yes, I would prefer to use a proper shell. No, I cannot switch to a better shell.
I have a very simplistic script:
/tmp/env_test.csh
#!/bin/csh -f
env
When I run this script from my user that is logged in with a tcsh shell, SHELL equals /bin/tcsh. When I run this script from cron, SHELL equals /bin/sh.
Why is the SHELL not being updated appropriately? What do I need to do to resolve this issue?
Look into man 1 csh. The section Pre-defined and environment variables lists which variables csh defines or respects. There is a variable shell in lowercase:
shell The file in which the shell resides. This variable is used in
forking shells to interpret files that have execute bits set,
but which are not executable by the system. (See the descrip-
tion of Non-builtin Command Execution below.) Initialized to
the (system-dependent) home of the shell.
So let's have a look:
% echo $shell
/bin/csh
echo $shell returns /bin/tcsh from the script, but env | grep -i shell does not find the correct variable in cron. It was my understanding from other places (such as this answer) that $SHELL should be set. Indeed, in my active login shell, it is. The only place I don't get $SHELL is cron.
You should set the SHELL variable to /bin/csh in your crontrab, you can check the cron environment variable through:
* * * * * env > ~/cron-env
tail -f ~/cron-env
The default SHELL should be set to /bin/sh.
SO: How to simulate the environment cron executes a script with?
$SHELLis not set to the correct shell. When cron is running using/bin/sh,$SHELL=/bin/sh, even after launching a C-shell script (#!/bin/csh -f). Perlbrew then assumes it's a Bourne shell and uses Bourne shell commands to set up the environment. This happens despite runningsource <perlbrew path>/perlbrew/etc/cshrcprior to runningperlbrew use. I solved this by insertingsetenv SHELL /bin/cshto the perlbrew cshrc.