Extracting directory name from an absolute path using sed or awk

Question

I want to split this line

/home/edwprod/abortive_visit/bin/abortive_proc_call.ksh

to

/home/edwprod/abortive_visit/bin
         


        

Answer 1

For most platforms and Unix/Linux shells now available dirname:

dirname /home/edwprod/abortive_visit/bin/abortive_proc_call.ksh

Using of dirname is the simpliest way, but it is not recommended for cross platform scripting for example in the last version of autoconf documentation http://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Limitations-of-Usual-Tools.html#Limitations-of-Usual-Tools .

So my full featured version of sed-based alternative for dirname:

str="/home/edwprod/abortive_visit/bin/abortive_proc_call.ksh"
echo "$str" | sed -n -e '1p' | sed  -e 's#//*#/#g' -e 's#\(.\)/$#\1#' -e 's#^[^/]*$#.#' -e 's#\(.\)/[^/]*$#\1#' -

Examples:

It works like dirname:

• For path like /aa/bb/cc it will print /aa/bb
• For path like /aa/bb it will print /aa
• For path like /aa/bb/ it will print /aa too.
• For path like /aa/ it will print /aa
• For path like / it will print /
• For path like aa it will print .
• For path like aa/ it will print .

That is:

• It works correct with trailing /
• It works correct with paths that contains only base name like aa and aa/
• It works correct with paths starting with / and the path / itself.
• It works correct with any $str if it contains \n at the end or not, even with many \n
• It uses cross platform sed command
• It changes all combinations of / (// ///) to /
• It can't work correct with paths containing newlines and characters invalid for current locale.

Note Alternative for basename may be useful:

echo "$str" | awk -F"/" '{print $NF}' -