I use the single line
(cd ${FILENAME%/*}; pwd)However, this can only be used when $FILENAME has a leading path of any kind (relative or absolute) that actually exists. If there is no leading path at all, then the answer is simply $PWD. If the leading path does not exist, then the answer may be indeterminate, otherwise and the answer is simply ${FILENAME%/*} if the path is absolute.
Putting this all together I would suggest using the following function
function abspath() { # argument 1: file pathname (relative or absolute) # returns: file pathname (absolute) if [ "$1" == "${1##*/}" ]; then # no path at all echo "$PWD" elif [ "${1:0:1}" == "/" -a "${1/../}" == "$1" ]; then # strictly absolute path echo "${1%/*}" else # relative path (may fail if a needed folder is non-existent) echo "$(cd ${1%/*}; pwd)" fi}Note also that this only work in bash and compatible shells. I don't believe the substitutions work in the simple shell sh.
