7

Let me give an example (it's just an example taken from here):

$ ls -l /usr/bin/gnome-text-editor lrwxrwxrwx 1 root root 35 Mar 16 2015 /usr/bin/gnome-text-editor -> /etc/alternatives/gnome-text-editor $ ls -l /etc/alternatives/gnome-text-editor lrwxrwxrwx 1 root root 14 Mar 16 2015 /etc/alternatives/gnome-text-editor -> /usr/bin/gedit $ ls -l /usr/bin/gedit -rwxr-xr-x 1 root root 588064 Mar 27 2014 /usr/bin/gedit

Here you can see that I've to use ls -l three times for reaching to destination. (3rd time is for making sure that /usr/bin/gedit is not a link`)

Is there any way (by means of making script or another command etc.) that I can get expected output like:

$ <improved ls -l> /usr/bin/gnome-text-editor lrwxrwxrwx 1 root root 35 Mar 16 2015 /usr/bin/gnome-text-editor -> /etc/alternatives/gnome-text-editor lrwxrwxrwx 1 root root 14 Mar 16 2015 /etc/alternatives/gnome-text-editor -> /usr/bin/gedit

Another good output may be:

$ <some-command> /usr/bin/gnome-text-editor /usr/bin/gnome-text-editor > /etc/alternatives/gnome-text-editor > /usr/bin/gedit
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  • Also be aware, that links can be circular: a -> b b -> a Commented Mar 18, 2016 at 16:00

3 Answers 3

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13

In this case, that's a Debian "alternative", so to get more details, you could use:

$ update-alternatives --display gnome-text-editor gnome-text-editor - auto mode link best version is /usr/bin/gedit link currently points to /usr/bin/gedit link gnome-text-editor is /usr/bin/gnome-text-editor slave gnome-text-editor.1.gz is /usr/share/man/man1/gnome-text-editor.1.gz /usr/bin/gedit - priority 50 slave gnome-text-editor.1.gz: /usr/share/man/man1/gedit.1.gz /usr/bin/leafpad - priority 40 slave gnome-text-editor.1.gz: /usr/share/man/man1/leafpad.1.gz

More generally, on Linux, you can use the namei command to know about all the symlinks involved in the resolution of a path (also mount points with -x):

$ namei -lx /usr/bin/gnome-text-editor f: /usr/bin/gnome-text-editor Drwxr-xr-x root root / drwxr-xr-x root root usr drwxr-xr-x root root bin lrwxrwxrwx root root gnome-text-editor -> /etc/alternatives/gnome-text-editor Drwxr-xr-x root root / drwxr-xr-x root root etc drwxr-xr-x root root alternatives lrwxrwxrwx root root gnome-text-editor -> /usr/bin/gedit Drwxr-xr-x root root / drwxr-xr-x root root usr drwxr-xr-x root root bin -rwxr-xr-x root root gedit

For a more direct answer to your question, I'd do something like:

#! /bin/zsh - zmodload zsh/stat || exit ret=0 for file do n=0 while ls -ld -- "$file" || ! ret=1 && [ -L "$file" ] do if ((++n > 40)) && [ ! -e "$file" ]; then echo >&2 too many symlinks ret=1 break fi zstat -A target +link -- "$file" || ! ret=1 || break case $target in (/*) file=$target;; (*) file=$file:h/$target esac done done exit "$ret"

That may not give you all the information you need to understand what's going on. Compare for instance:

$ ./resolve-symlink b/b/b/b/x/b lrwxrwxrwx 1 stephane stephane 1 Mar 18 15:37 b/b/b/b/x/b -> a lrwxrwxrwx 1 stephane stephane 4 Mar 18 15:37 b/b/b/b/x/a -> ../a lrwxrwxrwx 1 stephane stephane 26 Mar 18 15:15 b/b/b/b/x/../a -> /usr/bin/gnome-text-editor lrwxrwxrwx 1 root root 35 Nov 5 2013 /usr/bin/gnome-text-editor -> /etc/alternatives/gnome-text-editor lrwxrwxrwx 1 root root 14 Mar 15 12:21 /etc/alternatives/gnome-text-editor -> /usr/bin/gedit -rwxr-xr-x 1 root root 10344 Nov 12 17:18 /usr/bin/gedit

With:

$ namei -lx b/b/b/b/x/b f: b/b/b/b/x/b lrwxrwxrwx stephane stephane b -> . drwxr-xr-x stephane stephane . lrwxrwxrwx stephane stephane b -> . drwxr-xr-x stephane stephane . lrwxrwxrwx stephane stephane b -> . drwxr-xr-x stephane stephane . lrwxrwxrwx stephane stephane b -> . drwxr-xr-x stephane stephane . lrwxrwxrwx stephane stephane x -> 2 drwxr-xr-x stephane stephane 2 lrwxrwxrwx stephane stephane b -> a lrwxrwxrwx stephane stephane a -> ../a drwxr-xr-x stephane stephane .. lrwxrwxrwx stephane stephane a -> /usr/bin/gnome-text-editor Drwxr-xr-x root root / drwxr-xr-x root root usr drwxr-xr-x root root bin lrwxrwxrwx root root gnome-text-editor -> /etc/alternatives/gnome-text-editor Drwxr-xr-x root root / drwxr-xr-x root root etc drwxr-xr-x root root alternatives lrwxrwxrwx root root gnome-text-editor -> /usr/bin/gedit Drwxr-xr-x root root / drwxr-xr-x root root usr drwxr-xr-x root root bin -rwxr-xr-x root root gedit
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10

readlink is the command you are looking for.

$ readlink -e /usr/bin/gnome-text-editor /usr/bin/gedit

Various flags (-f, -e, -m) are available according to how you'd like to behave in case of broken links - see man readlink for details.

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  • Thanks; but it doesn't give the information about intermediate file(s) (like /etc/alternatives/gnome-text-editor) which may be useful Commented Mar 18, 2016 at 16:05
2

You can use the following script:

$ cat myll #!/bin/bash name="$1" while [[ -L "$name" ]]; do ls -l "$name"; name=`readlink "$name"`; done

Example output:

$ myll /usr/bin/gnome-text-editor lrwxrwxrwx 1 root root 35 Mar 16 2015 /usr/bin/gnome-text-editor -> /etc/alternatives/gnome-text-editor lrwxrwxrwx 1 root root 14 Mar 16 2015 /etc/alternatives/gnome-text-editor -> /usr/bin/gedit

Here [[ -L "$name" ]] checks whether file is link or not and readlink "$name" reads link and save it to variable name for next loop. And hence while [[ -L "$name" ]] loops until original target/file reached.

For second work-around, you can use:

#!/bin/bash name="$1" while [[ -L "$name" ]]; do echo -n "$name > "; name=`readlink "$name"`; done echo "$name"

Example output:

$ myls /usr/bin/gnome-text-editor /usr/bin/gnome-text-editor > /etc/alternatives/gnome-text-editor > /usr/bin/gedit
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  • 2
    That won't work properly for relative symlinks (as relative symlinks are relative to the symlink's host directory, not to your current working directory). Commented Mar 18, 2016 at 14:57

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