ctime, mtime and atime; find command

ctime, mtime  and atime are very useful commands when dealing with time related search commands in the linux Family of operating systems.

ctime; Linux find command

ctime; Linux find command

This post is about how to use them in

a simple but yet very powerful way. Let’s get to it:

Let say you want to find all files in a folder that follow/fulfill the following criteria:

  1. the folder is /vat/lib/mysql/data
  2. The file name contains: mysql-bin.
  3. The files are younger than 2 days.

In other words find all the mysql binary log files that are not older than 2 days. I am using mysql binary logs of a server as an example here, but the same might apply to any type of files and folders.

ctime; Here is the command :

$ find /var/lib/mysql/data -ctime -2 -name 'mysql-bin.*' 
/var/lib/mysql/data/mysql-bin.007989
/var/lib/mysql/data/mysql-bin.007988
/var/lib/mysql/data/mysql-bin.007990
/var/lib/mysql/data/mysql-bin.007994
(...)
$

if you see the output it magically shows the files wanted. Isn’t that great? Not let’s break it in smaller pieces.

  • find is the command that says you will try to find something to the OS.
  • then next the path where you want to find stuff.
  • Then -ctime -2, this means creation time is younger than 2, here you can also say different stuff:
    1. For instance any integer positive number you add here will be the MAX age of the files to find. technically 2 means 3 days, but aside from that is regular find younger than x days.
      According to the docs:
                  -mtime n
                    File's data was last modified n*24 hours ago.  See the
                    comments for -atime to understand how rounding affects the
                    interpretation of file modification times.
                  -atime n
                    File was last accessed n*24 hours ago.  When find figures out
                    how many 24-hour periods ago the file was last accessed, any
                    fractional part is ignored, so to match -atime +1, a file has
                    to have been accessed at least two days ago.
    2. Then the last part is just to find by name. -name ‘mysql-bin.*’ any file or directory who’s name starts with mysql-bin., * means wildcard or anything.

Ok so we got a command now you should know the main parameters and be able to find help if needed:

  1. ctime is creation time in days.
  2. mtime is modification time in days.
  3. atime is access time in days.
  4. cmin same as -ctime, but in minutes
  5. mmin same as -mtime but in minutes
  6. amin same as -atime but in days.

Find has many other parameters that help you filter by other many parameters, you can just execute man and check them out or make s simple search in google. Another thing you need to keep present is the sign of the integer number, e.g.:

  1. mtime -3 means younger than 3+1 days.
  2. atime 5 means exactly between 5 and 6 days.
  3. ctime +4 means older than 4+1 days.
  4. Then you can combine statements like ‘-ctime +2 -ctime -4’ which means between those two numbers (remember the +1 so it would be between 3 and 5).

And with this you can create fun and useful commands that will ease your serch. e.g.:

Remove everything older than one month in the path recoursively:

find ~/abelworld/files -ctime +30 -exec rm -rf '{}' ';'

 Find everything create in the folder between 1 and 3 months and the name ends in .txt:

find ~/abelworld/files -mtime +30 -mtime -60  -name '*.txt'

And that is all for today. I hope you found it usefull and feel free to comment on any other cool usage for the find command.

Posted in Tips

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