2011-08-09, 11:29(+02), Bernd Eggink:
> On 09.08.2011 03:44, Jon Seymour wrote:
>> Has anyone ever come across an equivalent to Linux's readlink -f that
>> is implemented purely in bash?
>
> You can find my version here:
>
> http://sudrala.de/en_d/shell-getlink.html
>
> As it contains some corrections from Greg Wooledge, it should handle
> even pathological situations. ;)
[...]
> function getlink # ([-l] path)
Why use the ksh syntax instead of the standard one?
> {
> # Path of the file a symbolic link is pointing to.
> # -l: follow link chain, print last target
> # no option: print 1st target unchanged
>
> typeset dir file last link opt oldPWD=$PWD ret=0
>
> (( OPTIND = 1 ))
>
> while getopts "l" opt
> do
> case $opt in
> (l) last=1
> ;;
> esac
> done
>
> shift $(( OPTIND - 1 ))
> file=$1
>
> if [[ $last ]] # last link
> then
> while true
> do
> dir=$(dirname "$file")
What if $file starts with "-"?
> [[ ! -d $dir ]] &&
> {
> ret=1
> break
> }
>
> # remove slashes at end
>
> while [[ $file == */ ]]
> do
> file=${file%/}
> done
What if $file is "/"
> file=${file##*/} # file name
> command cd -P "$dir"
What if that command fails?
> [[ ! -h $file ]] && break
What if there are symlinks in the path components?
> link=$(command ls -l -- "$file"; printf x)
Good point about command substitution discarding trailing
newlines. I forgot that in the solution I gave.
> link=${link%$'\nx'}
> remove="$file -> "
> file=${link#*"$remove"}
> done
>
> printf "%s\n" "$PWD/$file"
> command cd $oldPWD
What if $oldPWD has blanks or wildcards?
> elif [[ ! -h $file ]] # 1st link
> then
> printf "%s\n" "$file"
> else
> link=$(ls -l "$file")
> printf "%s\n" "${link##*-> }"
What about trailing newlines here and links with "-> " in their
path.
> fi
>
> return $ret
What if $IFS contains 0 or 1?
> }
>
> declare -fc getlink
What's the -c about?
--
Stephane
