topic Re: Finding absolute path of 'sourced' shell script in Operating System - HP-UX

Finding absolute path of 'sourced' shell script

vinay naik — Tue, 18 Aug 2009 08:53:16 GMT

We use a ksh script which is sourced from different directories. This script sets project paths and other environment variables based on the absolute path of the script.
The issue is that the path of this script is not fixed as it changes based on the directory it is checked out.
If it is sourced from a different directory the $PWD or `dirname` displayed is that of the directory which sources it and 'not' the directory of the 'sourced script'.

Can someone please suggest a solution for this ?

Re: Finding absolute path of 'sourced' shell script

Berd — Tue, 18 Aug 2009 08:57:41 GMT

Vinay,

You could use the 'which' command prior to executing. This would tell you which, pardon the pun, sourced script you are executing.

HTH

Regards,
Berd

Re: Finding absolute path of 'sourced' shell script

Dennis Handly — Tue, 18 Aug 2009 09:24:32 GMT

Since a sourced file isn't a script, I don't think there is any way to get the path except have the caller set a variable.

Sourced files do undergo $PATH lookup, not sure if that is helpful.

Re: Finding absolute path of 'sourced' shell script

Hakki Aydin Ucar — Tue, 18 Aug 2009 10:05:31 GMT

to put a which OR find to source every time script run will have negative effect as a big delay.

why do not you consider a copy of source to known directory on your local ?

Re: Finding absolute path of 'sourced' shell script

Bill Hassell — Wed, 19 Aug 2009 02:29:00 GMT

Actually, "which" and "whereis" are deprecated because they do not match what the shell will do. The correct (and only useful) command is whence and whence -v. whence -v is so useful that it is always aliased to the "type" command. Things like $PWD are useless because users can change the contents and you never want to use a relative pathname (a sourced script always starts with: /)

To see why which and whereis are not useful:

which for
whereis for
whence -v for

The only correct answer is whence -v for. This is even more telling:

which type
whereis type
whence -v type

which and whereis both report that /usr/bin/type is the location of the command but your script will *not* run /usr/bin/type. Instead, it will run the alias. This is critically important for sourced scripts and other commands that a user may have aliased or have $PATH set to unsafe locations.

I will explictly set PATH and unset all aliases in my critical scripts to prevent accidents (or hacks):

export PATH=/usr/bin:/usr/sbin:/usr/contrib/bin
unalias -a

Re: Finding absolute path of 'sourced' shell script

Dennis Handly — Wed, 19 Aug 2009 07:20:08 GMT

>Bill: "which" and "whereis" are deprecated because they do not match what the shell will do.

I always think of them as scummy C shell commands, not to be used for a real shell, unless you have a bad path setting.

Re: Finding absolute path of 'sourced' shell script

Berd — Wed, 19 Aug 2009 09:22:54 GMT

Bill / Dennis - I will never again use which, whence is the way !

Berd