mjhjmtu

I have a script which finds files in the directory specified by user.

#!/bin/bash

# make sure about the correct input
if [ -z $1 ]
then
 echo "Usage: ./script_name.sh path/to/directory"
else
 DIR=$1
 if [ $DIR = '.' ]
 then 
 echo "Find files in the directory $PWD"
 else 
 echo "Find files in the directory $DIR"
 fi

 find $DIR -type f -exec basename ; 
fi

if I input

$ ./script_name.sh .

script gives me correct substitution ./ to $PWD and shows (for example)

$ Find files in the directory /root/scripts 

But I can't make a decision how to substitute ../ to the name of the directory immediately above in the hierarchy. If I input

$ ./script_name.sh .. 

script gives me the output

$ Find files in the directory .. 

Does anybody know how to substitute ../ to the actual name of the directory?

GNU coreutils has the realpath command that does just that.

/tmp/a$ realpath ..
/tmp

Though note that if the path contains symlinks, it will also resolve those:

/tmp/b/c$ realpath ..
/tmp/x/y

(Here, /tmp/b was a symlink to /tmp/x/y/)

This may be different from what the shell does with cd ... E.g. cd ../.. from /tmp/b/c in Bash shows the new path as /tmp/, not as /tmp/x.

A few ideas:

parent="$(dirname "$(pwd)")"

parent="$(
 cd ..
 pwd
)"

You could first cd to .. and then use the $PWD.