Can I run the nohup command from tcsh

Question

I am looking into the nohup command and I am not sure which shells it support. It seems as if this program works differently in bash and tcsh. What I tried was something very simple.

nohup --help

When I start it from bash it works just fine, but for tcsh is says,

--help: Command not found.

This does definitely not mean the command not works, but this is a confusing indicator. Due to that the settings on the machine I run on seems to keep programs a fairly long time before they terminate, it is hard to actually verify that nohup is working.

Another indicator that things no works as expected is that when running the script I plan to run it does also work differently. When running in bash it will output to nohup.out, while in tcsh it does not (it outputs to the terminal I run the nohup command in).

Any ideas?

Tested on both rhel6 and rhel7

Answer 1

When in bash, using nohup will use the external utility nohup. The GNU coreutils' version of nohup does indeed have a --help flag that will output some information.

When in tcsh, using nohup will use the shell's built-in command nohup, even in an external utility of the same name exists. See the tcsh manual for more information about the built-in nohup in that shell.

To use GNU coreutils' nohup in tcsh, use the utility with its full path, e.g., /usr/bin/nohup --help.