How to find path from where current process/executable is running?

Question

I am running some executables while connected to a local unix server box.

Say, I'm trying to run an executable 'abc'. Now the server might have provided an alias for 'abc'.. How do I get to know of this path? As in, if I invoke 'abc', it might actually run it from, say, /opt/corp/xyz/abc .. How do I get to know from what path I'm invoking the executable?

By the way I'm running on HP-UX :D

Answer 1

"which abc" to show which abc you would be calling

or "alias" to list aliases

perhaps "echo $0" from inside a script, or retrieving argv[0] some other way.

Answer 2

Does HP-UX have the "which" command? Run:

which abc

If you have it, the which command will tell you which abc program will run from your $PATH.

Answer 3

If you are running using the PATH environment variable, you could try:

$ which abc

or

$ whereis abc

If there is a symbolic link for the command and you want to know the *"real"* target, you can use something like:

$ readlink /opt/corp/xyz/abc

I do not have access to an HPUX system in front of me right now, but this should work:

$ ls -l /opt/local/bin/wish
lrwxr-xr-x  1 root  admin  22 Feb  3 21:56 /opt/local/bin/wish@ -> /opt/local/bin/wish8.5
$ readlink /opt/local/bin/wish
/opt/local/bin/wish8.5

If the command is based on an alias, the following will reveal the alias definition.

$ alias abc

depending on how your system is configured, the above commands should provide answers to multiple variations of your question.

in Perl:

$running_script = $0;

from Python, see SO http://stackoverflow.com/questions/606561/how-to-get-filename-of-the-main-module-in-python

Answer 4

From a command line terminal:

$ which abc

/opt/corp/xyz/abc

Answer 5

Thanks all! 'which' was the commmand I was after! I'm facepalming myself now as I had already known the command (in Ubuntu).. And it does work like a charm in HP-UX!

EDIT : 'whereis' suggested by popcnt is even more appropriate! Thanx a lot man!

Answer 6

The correct way to get the path of a script on Unix is:

dir=$(cd $(dirname "$0"); pwd)

Background: $0 is the filename+path of the script relative to the current directory. It can be absolute (/...) or relative (../, dir/...). So the $(dirname "$0") returns the path (without the filename). Mind the quotes; "$0" can contain spaces and other weird stuff.

We then cd into that directory and pwd will return the absolute path where we end up.

Works for ksh and bash.

In a C program, you should check argv[0]. I'm not sure whether the shell will put the complete path in there. If you have trouble, I suggest to wrap your executable in a small script which prepares the environment and then invoke your executable with:

exec "$dir/"exe "$@"