I wonder whether there's some rather simple shell incantation to calculate the disk usage of a directory (using the du command) but with the following requirements: symlinks that point to files/subdirectories inside the directory should not be followed, but symlinks to outside files/subdirectories should. Or whether I need to do some scripting to accomplish this.
du: Follow symlinks if symlink points to outside directories, don't follow otherwise
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1 Answers
Unless I have missed something in your question, du already does that when instructed to follow symlinks (-L).
I got two trees:
tree1/:
├── dir1
│ └── file
├── dirA -> ../tree2/dirA
└── link1 -> dir1
and tree2/:
.
└── dirA
└── file
File is in both cases 1MB in size.
Now run du -shL on tree1/:
$ du -shL tree1
2.0M tree1
While file can be seen three times in tree1/ when following symlinks:
$ find tree1 -follow -type f
tree1/dirA/file
tree1/link1/file
tree1/dir1/file
It only counted twice towards the total. Namely once from tree1/ and once linked in from tree2/dirA/ (or what I understood as you meaning from outside / not being sub-directories of tree1/).
It would also seem to make sense, because being links inside the same tree, they do not really consume additional disk space (beyond the symlink entry).
I've also grown the tree1 a bit to:
.
├── dir1
│ └── file
├── dir2
│ └── file -> ../dir1/file
├── dirA -> ../tree2/dirA
└── link1 -> dir1
And ran:
$ du -abcL .
1048576 ./dir2/file
1048636 ./dir2
1048576 ./dirA/file
1048636 ./dirA
60 ./link1
2097452 .
2097452 total
As you can see, links only count towards total / size of . with size of link entry (even though I admit 60 confuses me a but, I'd expect 4) and not (dereferenced) content of the file they point to.
Is this what you wanted or close enough?
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