Re: [PLUG] Determining when a shell script is sourced

[brent timothy saner <brent.saner@gmail.com>]

On 4/18/19 5:27 PM, K.S. Bhaskar wrote:
> We have a shell script (starts with #!/binsh and is at
> https://gitlab.com/YottaDB/DB/YDB/blob/master/sr_unix/ydbinstall.sh)
> that should preferably not be source'd. Is there a way to test within
> the script whether someone has source'd it and generate an error without
> terminating the shell session that source'd it? Thank you very much.
> 
> Regards
> – Bhaskar
> 


https://stackoverflow.com/a/28776166/11365825 is probably the best
answer on this; a lot of it depends on whether your /bin/sh is linked to
bash, or if you need it to be POSIX-capable (i.e. /bin/sh is actually
Bourne instead of Bourne Again, or it's ASh, or something).

a couple big problems are:

- the $BASH_SOURCE array is bash-only

- $BASH_SOURCE doesn't reliably detect if something is sourced or not,
just if it's an interactive command entered vs. from a file (invoked or
sourced)

- $_ doesn't work very reliably; you have ONE shot to capture it in the
script before it goes wonky:

$ echo 'this is an interactive command'
this is an interactive command
$ echo $_
this is an interactive command
$ /tmp/test.sh
/tmp/test.sh
$ . /tmp/test.sh
_filedir
$ . /tmp/test.sh
/tmp/test.sh

$ cat /tmp/test.sh
#!/bin/bash

echo ${_}


I'd stick to the POSIX-compat snippet in the answer I linked on SO,
since that has the least chance of futzing up.

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