How to extract directory path from file path?

In Bash, if VAR="/home/me/mydir/file.c", how do I get "/home/me/mydir"?

dirname and basename are the tools you're looking for for extracting path components:

$ VAR='/home/pax/file.c'
$ DIR="$(dirname "${VAR}")" ; FILE="$(basename "${VAR}")"
$ echo "[${DIR}] [${FILE}]"
[/home/pax] [file.c]

They're not internal bash commands but they are part of the POSIX standard - see dirname and basename. Hence, they're probably available on, or can be obtained for, most platforms that are capable of running bash.

$ export VAR=/home/me/mydir/file.c
$ export DIR=${VAR%/*}
$ echo "${DIR}"
/home/me/mydir

$ echo "${VAR##*/}"
file.c

To avoid dependency with basename and dirname

On a related note, if you only have the filename or relative path, dirname on its own won't help. For me, the answer ended up being readlink.

fname='txtfile'    
echo $(dirname "$fname")                # output: .
echo $(readlink -f "$fname")            # output: /home/me/work/txtfile

You can then combine the two to get just the directory.

echo $(dirname $(readlink -f "$fname")) # output: /home/me/work

If you care target files to be symbolic link, firstly you can check it and get the original file. The if clause below may help you.

if [ -h $file ]
then
 base=$(dirname $(readlink $file))
else
 base=$(dirname $file)
fi

HERE=$(cd $(dirname $BASH_SOURCE) && pwd)

where you get the full path with new_path=$(dirname ${BASH_SOURCE[0]}). You change current directory with cd new_path and then run pwd to get the full path to the current directory.