16.17 Getting Directory Name from a File's Pathname

When you write shell scripts or functions, sometimes you have a file's absolute pathname but need the parent directory's name. (You might need the parent's name to see if you have write permission in the directory - say, to remove or rename the file.)

If the pathname is stored in a csh shell (not environment) variable, use the modifier :h ( 9.6 ) . In the Bourne shell, see if your system has the dirname ( 45.18 ) command. If it doesn't, you can get the GNU version from the Power Tools disc - or use expr ( 45.28 ) with a regular expression ( 26.4 ) that gives you everything up to (but not including) the last slash. For example, if the pathname /home/mktg/fred/afile is stored in the shell variable file , these csh and sh commands would store /home/mktg/fred into the variable dir :

% 

set dir=$file:h

 $ 

dir=`dirname "$file"`

 $ 

dir=`expr "$file" : '\(.*\)/'`

To handle multiple pathnames, give this regular expression to sed ( 34.24 ) :

@	% ... sed 's@/[^/]*$@@' ...