10 Interesting Linux Command Line Tricks and Tips Worth Know

I passionately enjoy working with commands as they offer more control over a Linux system than GUIs(Graphical User Interfaces) applications, therefore am always on the look out to discover or figure out interesting ways and ideas to make Linux so easy and fun to operate, primarily from the terminal.

It is always thrilling when we discover new tricks or tips while using Linux especially a command line geek like myself.

Suggested Read: 5 Interesting Command Line Tips and Tricks in Linux – Part 1

And the feeling of wanting to share newly learned practices or commands with millions of Linux users out there, particularly the newbies who are still getting their way around this exciting operating system normally sets in.

Suggested Read: 10 Useful Linux Command Line Tricks for Newbies – Part 2

In this article, we will review a number of useful command line tricks and tips that can significantly enhance your Linux usage skills.

1. Lock or Hide a File or Directory in Linux

The simplest way of locking a file or directory is by using Linux file permissions. In case your the owner of a file or directory, you can block (remove read, write and execute privileges) other users and groups from accessing it as follows:

$ chmod 700 tecmint.info OR $ chmod go-rwx tecmint.info

To know more about Linux file permissions, read this article Managing Users & Groups, File Permissions & Attributes in Linux.

To hide the file/directory from other system users, rename it with a (.) at the start of the file or directory:

$ mv filename .tecmint.info 2. Translate rwx Permissions into Octal Format in Linux

By default, when you run the ls command, it displays file permissions in rwx format, but to understand the equivalence of this format and the octal format, you can learn how to translate rwx permissions into Octal format in Linux.

3. How to Use ‘su’ When ‘sudo’ Fails

Although sudo command is used to execute commands with superuser privileges, there are moments when it fails to work as in the example below.

Here, I want to empty the contents of a large file named uptime.log but the operation has failed even when I used sudo.

$ cat /dev/null >/var/log/uptime.log $ sudo cat /dev/null >/var/log/uptime.log

Empty Large File Content in Linux

In such as case, you need to switch to the root user account using su command to perform the operation like so:

$ su $ sudo cat /dev/null >/var/log/uptime.log $ cat /var/log/uptime.log

Switch to Super User

Try to understand the difference between su and sudo, in addition, read through their man pages for more guidelines:

$ man sudo $ man su 4. Kill a Process in Linux

Sometimes when you want to terminate a process using kill or killall or pkill commands, it may fail to work, you realize that the process still continues to run on the system.

In order to destructively kill a process, send the -KILL siganl to it.

First determine its process ID and then kill it like so:

$ pidof vlc $ sudo kill -KILL 10279

Find and Kill Process in Linux

Check the kill command for additional usage options and information.

5. Delete File Permanently in Linux

Normally, we use the rm command to delete files from a Linux system, however, these files do not completely get deleted, they are simply stored and hidden on the hard disk and can still be recovered these files in Linux and viewed by another person.

To prevent this, we can use the shred command which overwrites the file content and optionally deletes the file as well.

$ shred -zvu tecmint.pdf

The options used in the above command:

-z – adds a final overwrite with zeros to hide shredding.

-u – helps to truncate and remove file after overwriting.

-v – shows progress.

Delete File Permanently in Linux

Read through shred man page for additional usage instructions:

$ man shred 6. Rename Multiple Files in Linux

You can rename multiple files in Linux on the go by invoking the rename command.

It renames the filenames supplied according to a rule specified in the first argument.

The command below renames all .pdf files to .doc, here ‘s/\.pdf$/\.doc/‘ is the rule:

$ rename -v ‘s/\.pdf$/\.doc/‘ *.pdf

Rename Multiple Files in Linux

The next example renames all files matching "*.bak" to strip the extension, where ‘s/\e.bak$//‘ is the rule:

7. Check for Spelling of Words in Linux