How to Use the alias Command

Rai    Linux     alias, bash, code, command, hack, Linux, rhel, shortcut, Tips, trick

Let us say you execute the command ‘ls –alh’ every time you need a long listing of files and directories. Now you want a shortcut to do this. Fortunately, you can do so by using the command alias.

The alias command is useful for creating shortcuts for long commands or for correcting typing mistakes.

To create a shortcut for ls, you can do this:

$ alias ls=”ls -alh”

Now, everytime you execute ls command, it will be run as if you are executing the whole ls –alh command. Be reminded that this will replace the existing ls command. You may use a different name for the new shortcut like so:

$ alias ll=”ls -alh”

However, once you exit the current terminal, the alias will not be saved. To make the alias permanent, you may edit the .bashrc file in user’s home directory:

$ vi ~rai/.bashrc

Then insert the alias command after the line that says #system wide functions and aliases. Save and exit.

That should do it!

How to Fix the Terminal After Viewing Binary File

Rai    Linux     binary, clear, command, Linux, reset, screen, terminal, text

Every now and then, I open up a file only to realize that it is a binary file (yes, I keep ignoring the warning that I am about to view a binary file, not text). Then the terminal ends up messy, or in other words, wonky. The characters have turned out in various colors, the lines are indented, and you can’t see what you are typing.

To fix it, run this command:

$ reset

As the name implies, this will reset the terminal back to its normal state.

Using Perl to Replace Text in Multiple Files

Rai    Linux     code, lines, Linux, multiple, perl, replace, script, search, text, vim, word

You can search and replace text inside multiple files using Perl. This is how you do it:

$ perl -i -pe 's/Windows/Linux/;' test*

This command will search for the word ‘Windows’ inside all files that begin with ‘test’. When it finds one, it will substitute it with the word ‘Linux’. This is useful if you have multiple files that contain the same text. Remember that you can use regular expressions to make searching flexible.

VIM Trick: How to Comment Multiple Lines

Rai    Linux     comment, debian, fedora, Linux, number, rhel, special, suse, text editor, ubuntu, vi, vim

If you need to comment out lines of text inside VIM, you can try this trick:

(Enter command mode in VIM)
:40,105s/^/#/g

This will insert the # character at the beginning of each line starting from line number 40 to line number 105.

If you cannot see the line numbers, do this:

(Enter command mode in VIM)
:set number

To remove the lines:
:set nonumber

This is quite handy if you need to comment out lines of codes in a script.

Backspace Key Not Working in PuTTY

Rai    Linux     Linux, putty, ssh, suse, unix, vim, windows

If you access your Linux machines from a Windows workstations by SSH, most probably you are using PuTTY. My new job requires me to work with SUSE Enterprise servers and to my surprise, the VIM on SLES is somewhat different from that of RHEL.

One example is the backspace key. It just won’t work in PuTTY connecting to SUSE server. I have to put the cursor before the character I want to delete and press the DELETE key. If you have this issue with PuTTY/SUSE too, this tip might help you.

Go to your PuTTY configuration -> Terminal -> Keyboard

Look for Change Sequences Sent By -> The Backspace Key

From there, select Control-H. Save your session and try it.

This one worked for me, hope this works for you too.