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I have to find the symbolic link which contains the longest folder name in a folder full of symbolic links. So far I have this:

find <folder> -type l -printf "%l\n"

I was wondering if there's any way to save the folder names while searching, something like this pseudo code:

if [length > max]
{
  max = length
  var = link
}

Thanks :)

  • What do you mean by longest folder name? Can you give some example and expect outcome? – Stéphane Chazelas Oct 31 '18 at 17:32
  • 1
    When you change your requirements, you should ask a separate question instead. Otherwise, that invalidates all the already given answers (which may still be useful for people having similar requirements as your original ones). – Stéphane Chazelas Oct 31 '18 at 17:34
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find /path/to/base -type l | awk -F/ 'BEGIN {maxlength = 0; longest = "" } length( $NF ) > maxlength { maxlength = length( $NF ); longest = $NF } END { print "longest was", longest, "at", maxlength, "characters." }'

To make the awk more readable:

BEGIN {
   maxlength = 0
   longest = ""
} 

length( $NF ) > maxlength { 
   maxlength = length( $NF )
   longest = $NF
} 
END { 
   print "longest was", longest, "at", maxlength, "characters." 
}

awk is great at dealing with delimited data. Since paths are delimited by /s, we use that as the field separator (with the -F switch), track the longest name we've seen with a longest variable, and its length in the maxlength variable. Some care and feeding to make the output sane if no links are found I shall leave as an exercise for the reader.

  • I'm really sorry, I asked a wrong question. Could you edit your comment to answer the new question? :) – user45124 Oct 31 '18 at 16:43
  • Done. If this answers your question, please click the ✔ to the left of the answer to indicate it has been answered to your satisfaction. – DopeGhoti Oct 31 '18 at 17:19
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With zsh:

zmodload zsh/stat
by_link_depth() {
  zstat -A REPLY +link -- ${1-$REPLY}
  REPLY=${REPLY//[^\/]}
}

defines a function that returns the slashes in the target of the symlink, then you can use it as a sorting method for your globs:

ls -ld -- **/*(D@O+by_link_depth[1])

Would list the symlink (@), including hidden ones (D) with the deepest target (O+by_link_depth, reverse-sorts by link depth, and [1] selects the first).

Here in /usr/bin:

$ ls -ld -- **/*(D@O+by_link_depth[1])
lrwxrwxrwx 1 root root 59 Oct  9 03:08 mptopdf -> ../share/texlive/texmf-dist/scripts/context/perl/mptopdf.pl
$ ls -lUd -- **/*(D@O+by_link_depth[1,3])
lrwxrwxrwx 1 root root 59 Oct  9 03:08 mptopdf -> ../share/texlive/texmf-dist/scripts/context/perl/mptopdf.pl*
lrwxrwxrwx 1 root root 61 Oct  9 03:09 pkfix-helper -> ../share/texlive/texmf-dist/scripts/pkfix-helper/pkfix-helper*
lrwxrwxrwx 1 root root 60 Oct  9 03:09 mkjobtexmf -> ../share/texlive/texmf-dist/scripts/mkjobtexmf/mkjobtexmf.pl*

If you only care about the max-depth link target and not the symlink that points to it, you can run zstat +link instead of ls -ld on that symlink, or you could instead define a resolve and by_depth function:

resolve() zstat -A REPLY +link -- ${1-$REPLY}
by_depth() REPLY=${REPLY//[^\/]}

and:

printf '%s\n' **/*(D@O+by_depth+resolve[1])

Where +resolve translates the symlink to its target for the glob expansion, and O+by_depth reverse-sorts by depth.

With bash (though the code below is in no way bash specific) and GNU utilities (your -printf is already GNU-specific), you could get something approaching with:

find . -type l -printf '%l\0%p\0' | gawk -v RS='\0' -v ORS='\0' -F / '
   {n = NF; getline; if (n > max) {max = n; file = $0}}
   END {if (max) print file}' | xargs -r0 ls -ld

Or for the deepest target only:

find . -type l -printf '%l\0' | gawk -v RS='\0' -F / '
   NF > max {max = NF; target = $0}
   END {if (max) print target}'

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