pipe of tar and tree commands?

Question

I would like to see the tree of a big compressed file (specifically only the second level of directories) so I used the following command: tar -tf tarfile | tree -L 2

But it outputs the tree of the directory I am in, not of the compressed file. The other commands work fine, for example if I do: tar -tf tarfile | less It lets me explore correctly the tarfile.

Am I doing something wrong or I can't use tree like other commands trough pipping? If not, is there any other way to only see the files till second level directories of a compressed file?

Answer 1

tree can accept a list of files from standard input via the --fromfile argument.

Reads a directory listing from a file rather than the file-system. Paths provided on the command line are files to read from rather than directories to search. The dot (.) directory indicates that tree should read paths from standard input.

So you may want to try something like:

tar -tf tarfile | tree --fromfile .

But sadly, the -L argument doesn't work when you read from standard input, at least on my machine.

Answer 2

Since tree does not read stdin, but instead traverses the actual directory structure (whether the current directory or the specified directories), you would need to post-process the table of contents of the tar file. If the tar file was created with full/absolute path names, you'll need to adjust the ranges to find your desired directory depth.

One option is awk:

tar -tf tarfile | awk -F/ 'NF == 3'

Another is cut (sorting uniquely so that child directories beyond level 2 don't cause the parent to be reported again):

tar -tf tarfile | cut -d/ -f1-3 | sort -u