One thing that Linux Guru’s and Terminal Wizards often argue is that it’s way quicker to use the command line to do anything in Linux than it is through menus and what not. While the jury is still out on this, there are a lot of things they know which do help put the ball in their court which can often take a lot of time exploring the terminal to discover. I’ve compiled a list of my favourite commands and tricks that I think that would have saved me a bunch of time if I’d been aware of them when I first ventured in to Linux.
1. Repeat Recent Commands:
Let’s say you’ve just ran a command but forgot you needed to run it as sudo, you can use !! to repeat it with the additional sudo at the beginning, as below:
alex:~$ apt-get install package alex:~$ sudo !! sudo apt-get install package
Additionally you’re able to use this to go back further than the last command by replacing the second ! for -n (where n is the number of commands ago you want to repeat).
alex:~$ ls alex:~$ cd dir alex:~$ cat file alex:~$ !-3 ls
How about if you want to reuse the arguments from the last command but not the command itself, well it can do that too:
alex:~$ ls /home/alex/Desktop alex:~$ cd !* cd /home/alex/Desktop
2. Replace String In Last Command:
The use of the following command allows you to repeat the last command but replacing a string within it, useful if you made a mistake or typo. The follow example shows correcting a path for a change directory command.
alex:~$ cd /this/dir/is/wrong alex:~$ ^wrong^right^ cd /this/dir/is/right
Chances are, you’ll come across a situation where you’ve seemingly borked a terminal. Maybe you used cat on the wrong file or a program tried to export some strange characters which changed the settings. The following command should get you back to a fresh terminal quickly and you can often run it even when you don’t think you can. If the screen is really borked, try hitting enter before hand, typing reset and hitting enter again.
4. Running A Command In The Background:
Adding an & after the command you run allows you to continue to use the terminal screen while keeping the process running. Below shows an example of opening gedit in the background but allowing me to continue using the terminal for other commands. Great for editing and compiling code with the minimal number of terminals open.
alex:~$ gedit &
Once ran it’ll give you the process ID which allows you to kill it easily once you’re done with it.
5. Exiting A Terminal & Keeping Background Processes Running:
If you’ve opened a bunch of processes in the background (as per previous command) but now you want to close the terminal screen but not these processes you can use the following to release the ownership of the processes and exit.
alex:~$ disown -a && exit
Similar to ‘top’ (which allows you to view tasks in real-time with other useful info such as memory and CPU usage) but it’s displayed in a much easier to understand and interactive. It allows you to kill tasks without entering its PID, search, filter, sort and a bunch of other features.
7. Reverse History Search:
Ctrl + r
Using this will allow you to start typing and it’ll find the last command that contained the string you’re typing, hitting enter will execute that command. For example:
alex:~$ cd /home/alex/this/is/a/dir ctrl+r & typing "a/dir" (reverse-i-search)`': cd /home/alex/this/is/a/dir
8. Piping (Combining) Commands:
Piping commands allows you to pass the data that would usually be outputted to be directly passed as an input to another command, for example below is a list command being passed in to the less command to allow for scrolling of the data. This will work for most commands and experimentation is the best form of learning in this case.
alex:~$ ls | less
9. Auto Complete Command & File Names:
Half way through typing a command you can hit the Tab key and it’ll auto complete the word for you, if there are more than one other possible combinations a double tap of it will show you the possibilities. This also works for directory and files and can save some serious typing time.
10. Other useful Keyboard Shortcuts:
A few other keyboard shortcuts that are also useful to know (and not always as obvious as they should be):
Ctrl + c – kill current process
Ctrl + z – put current process in to the background
Ctrl + l – clear the terminal
Ctrl + a – set cursor to the start of the line
Ctrl + e – set cursor to the end of the line
Ctrl + shift + c – copy
Ctrl + shift + c – paste