Tuesday, May 1, 2018

How to use FIND in Linux


With the right arguments, the FIND command is a powerful and flexible way to locate data on your system.

How to use FIND in Linux
Image by : 

Get the newsletter

Join the 85,000 open source advocates who receive our giveaway alerts and article roundups.
In a recent Opensource.com article, Lewis Cowles introduced the find command.
find is one of the more powerful and flexible command-line programs in the daily toolbox, so it's worth spending a little more time on it.
At a minimum, find takes a path to find things. For example:
find /
will find (and print) every file on the system. And since everything is a file, you will get a lot of output to sort through. This probably doesn't help you find what you're looking for. You can change the path argument to narrow things down a bit, but it's still not really any more helpful than using the ls command. So you need to think about what you're trying to locate.
Perhaps you want to find all the JPEG files in your home directory. The -name argument allows you to restrict your results to files that match the given pattern.
find ~ -name '*jpg'
But wait! What if some of them have an uppercase extension? -iname is like -name, but it is case-insensitive.
find ~ -iname '*jpg'
Great! But the 8.3 name scheme is so 1985. Some of the pictures might have a .jpeg extension. Fortunately, we can combine patterns with an "or," represented by -o.
find ~ ( -iname 'jpeg' -o -iname 'jpg' )
We're getting closer. But what if you have some directories that end in jpg? (Why you named a directory bucketofjpg instead of pictures is beyond me.) We can modify our command with the -type argument to look only for files.
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f
Or maybe you'd like to find those oddly named directories so you can rename them later:
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type d
It turns out you've been taking a lot of pictures lately, so let's narrow this down to files that have changed in the last week.
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f -mtime -7
More Linux resources
You can do time filters based on file status change time (ctime), modification time (mtime), or access time (atime). These are in days, so if you want finer-grained control, you can express it in minutes instead (cmin, mmin, and amin, respectively). Unless you know exactly the time you want, you'll probably prefix the number with + (more than) or (less than). But maybe you don't care about your pictures. Maybe you're running out of disk space, so you want to find all the gigantic (let's define that as "greater than 1 gigabyte") files in the log directory:
find /var/log -size +1G
Or maybe you want to find all the files owned by bcotton in /data:
find /data -owner bcotton
You can also look for files based on permissions. Perhaps you want to find all the world-readable files in your home directory to make sure you're not oversharing.
find ~ -perm -o=r
This post only scratches the surface of what find can do. Combining tests with Boolean logic can give you incredible flexibility to find exactly the files you're looking for. And with arguments like -exec or -delete, you can have find take action on what it... finds. Have any favorite find expressions? Share them in the comments!

No comments:

Post a Comment