Hey devs from all over the world 😊
Okay! I know I am a Frontend developer, but I really like Linux. Just hear me out!
Today, I want to tell you guys about some Linux shell operators that you absolutely can't live without while chaining commands. 🤯
Going forward, we need an example of a command to explain the operators on. Due to our current situation and my absolute hatred, I am using this one :
kill covid19 --force
I know it won't work! but, maybe because no one tried it before. 🙄
Let's dive right in, 🌊
Starting off, We have the write operator
> This one is used to write the output to a file. For example,
kill covid19 --force > res.txt
Wait a sec! This
> will overwrite the content of the file. If you care about
res.txt you will have to use the append
>> operator which will append the output to the content of the file.
Actually, The output operator
> is just a shorthand for
Is there a
Is there a
3>? Don't get carried away!✋
1> is for standard program output, while
2> is for error output. For example,
kill covid19 --force 1> res.txt 2> err.txt
I know you guessed it! Just flip it over
kill covid19 --force < doctorsList.txt
Okay, Let's say it's not that easy. What if we need more? You can chain commands one after the other using the AND operator
&& like this :
kill covid19 --force && rebuild
&& is an AND operator. It will only run the next program if the previous one exited successfully.
We also have an OR operator
kill covid19 || (I honestly don't know what to write here! 🤯)
This one will only run the next program if the previous one failed ( Let's hope It doesn't ).
No! We still have more.
Killing covid19 is gonna take some time 😔 We can use the ampersand
& at the end to make it run in the background. Leaving the terminal free to run any other programs like this :
kill covid19 &
Wait! I am saving the best for last. The most awesome pipe operator
| This one can pass the output of one program to the next. Let's try to count the number of lines killing covid19 will output. (cause why not!)
kill covid19 | wc -l
That's it for now. If you guys liked it, please let me know down in the comments section.
You could also check my
Know Your Linux series here on dev.to.
Also, I have a small recommendation -unpaid- for you guys, I have been hacking away my quarantine days and you could too. Check out tryhackme.com. It is super cool!
If you want to know more or if you would like a hacking wingman, hit me up on discord at
Happy coding 🔥🔥