Is there a command to recreate directory trees?

Question

I created a 'cron' subdirectory in /var/log/ . It is: /var/log/cron

Within /var/log/cron I've created numerous sub-directories to store my log files for cron jobs. I am wondering if there is a way to output mkdir to match the directory structure my automated jobs use.

For example these sub-directory structure exists within

| ronshome
|-- personal_growth
|   |-- building_your_relationship
|   |-- fun_things_that_make_life_worth_living
|   |-- hope_is_found
|   |-- life_lessons
|   |-- thought_of_the_day
|   |-- what_makes_a_good_friend
|   |-- what_my_friends_mean_to_me
|   `-- who_am_i

My desired output is:

mkdir /var/log/cron/ronshome
mkdir /var/log/cron/ronshome/personal_growth
mkdir /var/log/cron/ronshome/personal_growth/building_your_relationship
mkdir /var/log/cron/ronshome/personal_growth/fun_things_that_make_life_worth_living

etc.

Essentially if I need to do a server restore I would like to be able to use this to recreate the log directories.

Answer 1

You could just make a tar containing all the directories (not the files they contain). Something like

# if in bash, you need to enable recursive globs:
shopt -s globstar
# the trailing '/' is important! it only matches directories, not files.
tar --no-recursion -cvzf directories.tar.gz /var/log/cron/**/

then you can just extract your directories.tar.gz file to recreate the directory tree.

You could just as well use the same globbing to create a list of things to mkdir to put in a shell script, but that will put the burden of proper quoting of directory names on you, for no good reason: a tar file is specifically a file designed to allow you to recreate a directory tree from specification.

(I don't think --no-recursion is POSIX, but it's in GNU tar and bsdtar, and honestly, that's enough for any reasonably expected machine this is needed on :) )

Answer 2

Using mtree (available in the netbsd-mtree package on Debian), we can save a "specification" of a directory hierarchy in a text file:

$ mtree -p /var/log/cron -cd >var-log-cron.mtree

This prints the specification (-c) of the /var/log/cron directory hierarchy, omitting everything but the directories (-d) and saves it to a text file.

You can then compare another hierarchy with the stored specification using

$ mtree -f var-log-cron.mtree -p /var/log/cron -d

This would report extra or missing directories as well as metadata changes (timestamps, ownerships, filetypes).

To update the hierarchy according to the specification in the text file, use

$ mtree -f var-log-cron.mtree -p /var/log/cron -du

(Note the added -u.) This would recreate the hierarchy according to the stored specification.

Answer 3

for a quick solution, something along the lines of

find -type d   -print0  | gzip -9 > dirtree.gz
#    ^ direc-  ^ end 
#    tories      each
#      only    find in
#              a zero-
#                byte

gzip -d dirtree | xargs -0 mkdir -p 

if you don't need any information about ownership and acccess mode.

Answer 4

Based on Marcus's answer:

shopt -s globstar
printf 'mkdir %q\n' /var/log/cron/**/ > recreate.sh

will generate a sh script that will re-create the directories when run.

Bash's printf %q uses backslash escaping for its arguments. Newer Bash versions support an alternative ${var@Q} that uses quotation marks for somewhat more pleasant looking output (except when the string itself contains a single-quote, which will still be correctly processed but will look ugly); this is done at variable expansion time so it needs a temporary array variable:

shopt -s globstar
dirs=(/var/log/cron/**/)
printf 'mkdir %s\n' "${dirs[@]@Q}" > recreate.sh

Both options produce sh&bash-compatible quoting.

The external GNU Coreutils /bin/printf %q also uses single quotes (see also).

A third option (this time the output is Bash-specific) is to use declare -p to output a variable in a form that can be directly read back:

shopt -s globstar
dirs=(/var/log/cron/**/)
declare -p dirs > recreate.bash
echo 'mkdir -p "${dirs[@]}"' >> recreate.bash

Answer 5

rsync

You can use rsync first to include all directories and then exclude all files ^[1].

rsync -av -f"+ */" -f"- *" /path/to/src /path/to/dest/

or with older syntax ^[2]

rsync -a --include='*/' --exclude='*' source/ destination/ 

It may also work on different machines and not just locally adding user@host: e.g.

rsync -a --include='*/' --exclude='*' user1@src_host:source/ user2@dest_host:destination/ 

For more information, it is always close to us man rsync.