How do you find the directory of a command? [duplicate]

Question

Possible Duplicate:
Location of file folders of installed programs

For example the following are the same

# /usr/bin/php updateDatabase.php

# php updateDatabase.php

But how would I infer the location of the php command to be in /usr/bin?

Answer 1

You can use the whereis command to find the location of an executable binary on your system.

Example:

$ whereis ls
ls: /bin/ls /usr/share/man/man1/ls.1.gz

EDIT: From this answer to a similar question, you can also use the which command.

Example:

$ which ls
/bin/ls

Answer 2

When the program can be run without specifying the full path, then its directory is in your $PATH variable.

Run

$ echo $PATH
/home/cweiske/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games