Bash conditional execution

Question

I took this code from a script I found online :

[ $# = 0 ] && usage

If there are no parameters at the command line, then call the usage method (which print the help info).

The thing I don't understand is why does the script exits after calling usage? Shouldn't it simply continue to other code?

janos · Accepted Answer · 2013-10-12 07:47:56Z

2

There are multiple ways this can happen:

The usage method has an exit command in it
The usage method has a return 1 command (or other non-zero value) and the script is invoked with -e flag, for example #!/bin/sh -e shebang
The usage method has an operation that fails and the script is invoked with -e flag

Maybe there are more ways that I don't recall now.

Personally, I always use exit 1 as the last command in a usage method, so the behavior seems all natural to me.

answered Oct 12, 2013 at 7:47

janos

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Comments

Dmitry Matveev · Accepted Answer · 2013-10-12 02:39:53Z

2

It would carry on unless 'usage' executes 'exit' command

answered Oct 12, 2013 at 2:39

Dmitry Matveev

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