How can I check if a directory is on the path in Bash? [duplicate]

Question

Possible Duplicate:
Bash: Detect if user's path has a specific directory in it

Given a directory, how can I determine whether it's on the unix PATH? Looking for a shell script.

Thanks, Kevin

Answer 1

You can write:

if [[ :$PATH: == *:"$directory_you_want_to_check":* ]] ; then
    # O.K., the directory is on the path
else
    # oops, the directory is not on the path
fi

Note that this won't follow symbolic links, or anything like that; it's just a string comparison, checking if colon-$PATH-colon contains colon-directory-colon.

Answer 2

I usually prefer case -- posting this in order to make the set complete (-:

case :$PATH: in
  *:/home/you/bin:*)  ;;  # do nothing
  *) PATH=/home/you/bin:$PATH ;;
esac

Notice the leading and trailing colons on the case expression in order to simplify the pattern. With case $PATH you would have to compare to four different patterns, depending on whether the beginning and end of the match was at the beginning or end of the variable.

Answer 3

Quick and dirty: you can echo the (slightly modified) path through grep and check the return value:

pax> echo ":$PATH:" | grep :/usr/sbin:
:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:

pax> echo $?
0

pax> echo ":$PATH:" | grep :/usr/xbin:

pax> echo $?
1

By putting : at either end of both the path and the directory you're looking for, you simply the grep expression and ensure only complete paths are found. Otherwise, looking for /usr/bin may turn up /usr/bin/xyzzy for example.