How to find symbolic links where target path matches a pattern

findsymlink

I am trying to find all symlinks below current folder whose target contains 'Dropbox'

My best guess was:

find . -type l -iname '*Dropbox*'

But this returns nothing.

I want to find items such as:

com.adobe.illustrator.plist -> /Volumes/data/Dropbox (Personal)/Mackup/Library/Preferences/com.adobe.illustrator.plist
com.apple.Terminal.plist -> /Volumes/data/Dropbox (Personal)/Mackup/Library/Preferences/com.apple.Terminal.plist
com.noodlesoft.Hazel.plist -> /Volumes/data/Dropbox (Personal)/Mackup/Library/Preferences/com.noodlesoft.Hazel.plist

so that I can re-create the links without the (Personal) text. (If there's a way to do that with one line, that would be excellent!)

Best Answer

If your find supports -lname or -ilname (GNU extensions also supported by some BSDs (including macOS which your /Volumes suggest you might be using)).

find . -lname '*Dropbox*' -exec ls -ld {} +

Or case-insensitively:

find . -ilname '*dropbox*' -exec ls -ld {} +

If not (or even if yes if you want to do anything easily with those links or prefer a sorted list) and you have zsh (shipped by default on macOS), you could do:

zmodload zsh/stat
set -o extendedglob # for (#i) for case insensitive
link_match() {
  local target
  zstat -A target +link -- "${2-$REPLY}" &&
    [[ $target = $~1 ]]
}
ls -ld -- **/*(D@e:'link_match "(#i)*dropbox*"':)

Or to recreate the links:

zmodload zsh/stat
for l (**/*(D@))
  zstat -A target +link -- $l &&
    [[ $target = *"Dropbox (Personal)"* ]] &&
    rm -f -- $l &&
    ln -s -- ${target//" (Personal)"} $l

Note that any shell code can always be written on one line if need be, but I fail to see the point. Here, just join those lines together if you want it on one line.

To do something similar with bash and GNU or FreeBSD/macOS utilities, it's more complicated and would be less efficient:

LC_ALL=C find . -lname '*Dropbox (Personal)*' -exec bash -c '
  for l do
    target=$(readlink "$l" && echo .) || continue
    target=${target%??}
    rm -f "$l" &&
      ln -s -- "${target//" (Personal)"}" "$l"
  done' bash {} +

Related Solutions

Do Symbolic Links Affect Disk Usage? – Detailed Analysis

Symbolic links do take room, of course, but just the room it takes to store the name and target plus a few bytes for other metadata. The space taken by a symbolic link does not depend on the space taken by the target (after all, the target is not even required to exist).

Plain du reports the space taken by a directory tree on the disk. du -L reports the space that would be taken by a directory tree if all symbolic links were replaced by their target. The former is usually the useful information; for example, it's the space you'd recover if you deleted the tree, and it's (approximately) the space you need to back up the tree.

du on a directory tree shows (usually) a little more than the total of the file sizes. That's due to two things. First, du also counts directories, which take a little room to store file names and metadata. Second, du counts the disk space taken by a file, which can be different from the file size: the most common effect is that files take up an integer number of blocks (4kB on a typical Linux installation), so a 1-byte file can show as 4kB in du output; but compression (such as the primitive form provided by sparse files on just about every unix filesystem) can make the file size larger than its disk usage.

From the numbers you give, it appears that Thunar reports the sum of the sizes of the files in the directory tree, following symbolic links. It's actually saying so in a subtle way — it's claiming that the total size is 570.3 kB, not that the disk usage is 570.3 kB. What is not at all apparent from the user interface or documentation is that Thunar follows symbolic links when computing the size.

Which one is “right” is a subjective matter. du reports disk usage. Thunar reports total size following symbolic links. Creating a symbolic link has a negligible impact on disk usage, but by definition does change total-size-following-symbolic-links that Thunar reports.

How to make find follow most, but not all, symbolic links

The -prune primary tells find not to recurse under a directory.

find -L -path ~/.wine/dosdevices -prune -o -type f -name 'My Favorite Movie.*' -print

If you want to use -lname in your condition, you can't use the -L option, because -L causes most predicates to act on the target of the link, including -lname. My recommendation in that case would be to use both your home directory and the hard disk root as the roots of your search.

find ~ /mnt/hdd -xtype f -name 'My Favorite Movie.*'

You might run find ~ -type l … to gather a list of symbolic links and use them as additional roots.

( IFS=$'\n'; set -f;
  find ~ $(find ~ -type l -lname '/mnt/hdd/*') \
       -xtype f -name 'My Favorite Movie.*' )

If you really want to recurse under symbolic links, you can exclude specific symbolic links by target instead of by name. However you can only exclude a finite list, not a pattern or subtree this way.

find -L \( -samefile /exclude/this -o -samefile ~/and/that \) -prune -o \
     -type f -name 'My Favorite Movie.*' -print

You can use other criteria such as ! -writable (files that you don't have write permission to), but I don't think GNU find has a way to recurse under symbolic links only if their target text matches a certain expression.

You could build a find command that does almost what you want except for not excluding enough symbolic links, run find2perl to convert the query to a Perl script, and tweak the Perl script a bit. There are many switches of GNU find that find2perl doesn't recognize, however.

Best Answer

Related Solutions

Do Symbolic Links Affect Disk Usage? – Detailed Analysis

How to make find follow most, but not all, symbolic links

Related Question