August 2017 – Stephen R Lang

Before doing anything in Linux, it is also smart to have a rollback plan. Making blanket, recursive permission changes on a directory would certainly fall into this category!

Lets say you found a directory on your system where the file permissions were all 777, so you want to secure them a bit by changing the permissions over to 644. Something like:

[root@web01 ~]# find /var/www/vhosts/domain.com -type f -perm 0777 -print -exec chmod 644 {} \;

The paranoid among us will want to ensure we can revert things back to the way they were before. Thankfully there are two commands that can be used to either backup or restore permissions on a directory recursively: getfacl and setfacl

To backup all the permissions and ownerships within a given directory such as /var/www/vhosts/domain.com, do the following:

[root@web01 ~]# cd /var/www/vhosts/domain.com
[root@web01 ~]# getfacl -R . > permissions_backup

Now lets say you ran the find command, changed everything over to 644, then realized you broke your application cause it needed some files to be 664 or something, so you just want to roll back so you can investigate what happened.

You can roll back the permissions by running:

[root@web01 ~]# cd /var/www/vhosts/domain.com
[root@web01 ~]# setfacl --restore=permissions_backup

Backup entire servers permissions

If you wanted to backup the entire server’s permissions, you can do that by:

[root@web01 ~]# getfacl -R --absolute-names / > server_permissions_backup

And the restoration process remains the same:

[root@web01 ~]# setfacl --restore=server_permissions_backup

This is just a quick reference page for using find to do basic things.

Find is a pretty powerful tool that accepts a bunch of options for narrowing down your search. Some basic examples of stuff you can do are below.

Find a specific file type and extension older than 300 days and remove them

This will find files:
– Older than 300 days
– Is a file
– Match *.jpg
– Will not go into sub directories

This also works for those pesky directories that have millions of files.

First, always confirm the command will work before blindly removing files:

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find . -maxdepth 1 -type f -name '*.jpg' -mtime +300 | xargs ls -al

Once you verified that the files displayed are the ones you want removed, remove them by running:

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find . -maxdepth 1 -type f -name '*.jpg' -mtime +300 | xargs rm -f

Find files with 777 permissions

This will find all files that have 777 permissions:

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find . -type f -perm 0777 -print

This will find all files that do NOT have 777 permissions

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find / -type f ! -perm 777

Find Files with 777 Permissions and change to 644

Use caution with this, this is generally not smart to run blindly as it will go into subdirectories unless you set maxdepth.

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find . -type f -perm 0777 -print -exec chmod 644 {} \;

Find Directories with 777 Permissions and change to 755

Use caution with this, this is generally not smart to run blindly as it will go into subdirectories unless you set maxdepth.

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find . -type d -perm 777 -print -exec chmod 755 {} \;

Find empty directories

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find /tmp -type d -empty

Find all hidden files within a directory

[root@web01 ~]# find /path/to/directory -type f -name ".*"

Find files owned by user or group

[root@web01 ~]# cd /path/to/directory
[root@web01 ~]# find /var/www -user apache
[root@web01 ~]# find /var/www -group apache

Find files that were modified in the last 30 days

[root@web01 ~]# find / -mtime 30

Find files that were modified in the last hour

[root@web01 ~]# find / -mmin -60

Find files that were changed within the last hour
Note, this one is specified in minutes only!

[root@web01 ~]# find / -cmin -60

Find files that were accessed in the last 5 days

[root@web01 ~]# find / -atime 5

Find files that were accessed within the last hour
Note, this one is specified in minutes only!

[root@web01 ~]# find / -amin -60

Count files per directory with find
This one is useful when you need to find the top 10 directories that contain the most amount of files.

[root@web01 ~]# vim count-files-per-directory.sh
#!/bin/bash

if [ $# -ne 1 ];then
  echo "Usage: `basename $0` DIRECTORY"
  exit 1
fi

echo "Please wait..."

find "$@" -type d -print0 2>/dev/null | while IFS= read -r -d '' file; do 
    echo -e `ls -A "$file" 2>/dev/null | wc -l` "files in:\t $file"
done | sort -nr | head | awk '{print NR".", "\t", $0}'

exit 0

Now run it against the / directory:

[root@web01 ~]# bash count-files-per-directory.sh /
Please wait...
1. 	 768 files in:	 /usr/share/man/man1
2. 	 631 files in:	 /usr/lib64/python2.6
3. 	 575 files in:	 /usr/share/locale
4. 	 566 files in:	 /usr/share/vim/vim74/syntax
5. 	 496 files in:	 /usr/bin
6. 	 487 files in:	 /usr/share/man/man8
7. 	 393 files in:	 /usr/share/perl5/unicore/lib/gc_sc
8. 	 380 files in:	 /usr/include/linux
9. 	 354 files in:	 /usr/lib64/python2.6/encodings
10. 	 334 files in:	 /usr/share/man/man3

Or if you only need to run the search in a specific directory:

[root@web01 ~]# bash count-files-per-directory.sh /usr/share/man
Please wait...
1. 	 768 files in:	 /usr/share/man/man1
2. 	 487 files in:	 /usr/share/man/man8
3. 	 334 files in:	 /usr/share/man/man3
4. 	 124 files in:	 /usr/share/man/man5
5. 	 49 files in:	 /usr/share/man
6. 	 35 files in:	 /usr/share/man/ru/man8
7. 	 31 files in:	 /usr/share/man/man7
8. 	 27 files in:	 /usr/share/man/fr/man8
9. 	 25 files in:	 /usr/share/man/de/man8
10. 	 22 files in:	 /usr/share/man/ja/man8

Month: August 2017

Backing up permissions on directory

Find command examples