The fc Command Tutorial With Examples For Beginners

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The fc command, short for fix commands, is a shell built-in command used to list, edit and re-execute the most recently entered commands in to an interactive shell. You can edit the recently entered commands in your favorite editor and run them without having to retype the entire commands. This command can be helpful to correct the spelling mistakes in the previously entered commands and avoids the repetition of long and complicated commands. Since it is shell-builtin, it is available in most shells, including Bash, Zsh, Ksh etc. In this brief tutorial, we are going to learn to use fc command in Linux.

The fc Command Tutorial With Examples

List the recently executed commands

If you run “fc -l” command with no arguments, it will display the last 16 commands.

$ fc -l
507 fish
508 fc -l
509 sudo netctl restart wlp9s0sktab
510 ls -l
511 pwd
512 uname -r
513 uname -a
514 touch ostechnix.txt
515 vi ostechnix.txt
516 echo "Welcome to OSTechNix"
517 sudo apcman -Syu
518 sudo pacman -Syu
519 more ostechnix.txt 
520 wc -l ostechnix.txt 
521 cat ostechnix.txt 
522 clear

To reverse the order of the commands, use -r flag.

$ fc -l

You can suppress the line numbers using “-n” parameter.

$ fc -ln
nano ~/.profile
source ~/.profile
source ~/.profile
fc -ln
fc -l
sudo netctl restart wlp9s0sktab
ls -l
pwd
uname -r
uname -a
echo "Welcome to OSTechNix"
sudo apcman -Syu
cat ostechnix.txt 
wc -l ostechnix.txt 
more ostechnix.txt 
clear

Now you won’t see the line numbers.

To list the result staring from a specific command, simply use the line number along with -l option. For instance, to display the commands starting from line number 520 up to the present, we do:

$ fc -l 520
520 ls -l
521 pwd
522 uname -r
523 uname -a
524 echo "Welcome to OSTechNix"
525 sudo apcman -Syu
526 cat ostechnix.txt 
527 wc -l ostechnix.txt 
528 more ostechnix.txt 
529 clear
530 fc -ln
531 fc -l

To list a commands within a specific range, for example 520 to 525, do:

$ fc -l 520 525
520 ls -l
521 pwd
522 uname -r
523 uname -a
524 echo "Welcome to OSTechNix"
525 sudo apcman -Syu

Instead of using the line numbers, we can also use strings. For example, list the commands starting from “pwd” command up to the resent, just use the staring letter of that command (i.e p) like below.

$ fc -l p
521 pwd
522 uname -r
523 uname -a
524 echo "Welcome to OSTechNix"
525 sudo apcman -Syu
526 cat ostechnix.txt 
527 wc -l ostechnix.txt 
528 more ostechnix.txt 
529 clear
530 fc -ln
531 fc -l
532 fc -l 520
533 fc -l 520 525
534 fc -l 520
535 fc -l 522
536 fc -l l

To see everything between “pwd” to “more” command, you could use either:

$ fc -l p m

Or, use combination of first letter of the starting command command and line number of the ending command:

$ fc -l p 528

Or, just line numbers of starting and ending commands:

$ fc -l 521 528

All of these three commands will display the same result.

Edit and re-run the last command automatically

At times, you might misspelled a previous command. In such situations, you can easily edit the spelling mistakes of the command using your default editor and execute it without having to retype again.

To edit the last command and re-run it again, do:

$ fc

This will open your last command in the default editor.

The fc Command Tutorial With Examples For Beginners

As you see in the above screenshot, my last command was “fc -l”. You can make any changes in the command and re-run it automatically again once you save and quit the editor. This can be useful when you use long and complicated commands or arguments. Please be mindful that this also can be a destructive. For example, if the previous command was a deadly command like “rm -fr ”, it will automatically execute and you may lost your important data. So, be very careful before using command.

Change the default editor to edit commands

Another notable option of fc is “e” to choose a different editor to edit the commands. For example, we can use “nano” editor to edit the last command like below.

$ fc -e nano

This command will open the nano editor(instead of the default editor) to edit last command.

The fc Command Tutorial With Examples For Beginners

You may find it time consuming to use -e option for each command. To make the new editor as your default, just set the environment variable FCEDIT to the name of the editor you want fc to use.

For example, to set “nano” as the new default editor, edit your ~/.profile or environment file:

$ vi ~/.profile

Add the following line:

FCEDIT=nano

You can also use the full path of the editor like below.

FCEDIT=/usr/local/bin/emacs

Type :wq to save and close the file. To update the changes, run:

$ source ~/.profile

Now, you can just type to “fc” to edit the last command using “nano” editor.

Re-run the last command without editing it

We already knew if we run “fc” without any arguments, it loads the editor with the most recent command. At times, you may not want to edit, but simply execute the last command. To do so, use hyphen (-) symbol at the end as shown below.

$ echo "Welcome to OSTechNix"
Welcome to OSTechNix
$ fc -e -
echo "Welcome to OSTechNix"
Welcome to OSTechNix

As you see, fc didn’t edit the last command (i.e echo “Welcome to OSTechNix”) even if I used -e option.

Please note that some of the options are shell-specific. They may not work in other shells. For example the following options can be used in zsh shell. It won’t work in Bash or Ksh shells.

Display when the commands were executed

To view when the commands were run, use -d like below.

fc -ld
1 18:41 exit
2 18:41 clear
3 18:42 fc -l
4 18:42 sudo netctl restart wlp9s0sktab
5 18:42 ls -l
6 18:42 pwd
7 18:42 uname -r
8 18:43 uname -a
9 18:43 cat ostechnix.txt
10 18:43 echo "Welcome to OSTechNix"
11 18:43 more ostechnix.txt
12 18:43 wc -l ostechnix.txt
13 18:43 cat ostechnix.txt
14 18:43 clear
15 18:43 fc -l

Now you see the execution time of most recently executed commands.

We can also display the full timestamp of each command using -f option.

 fc -lf
1 4/5/2018 18:41 exit
2 4/5/2018 18:41 clear
3 4/5/2018 18:42 fc -l
4 4/5/2018 18:42 sudo netctl restart wlp9s0sktab
5 4/5/2018 18:42 ls -l
6 4/5/2018 18:42 pwd
7 4/5/2018 18:42 uname -r
8 4/5/2018 18:43 uname -a
9 4/5/2018 18:43 cat ostechnix.txt
10 4/5/2018 18:43 echo "Welcome to OSTechNix"
11 4/5/2018 18:43 more ostechnix.txt
12 4/5/2018 18:43 wc -l ostechnix.txt
13 4/5/2018 18:43 cat ostechnix.txt
14 4/5/2018 18:43 clear
15 4/5/2018 18:43 fc -l
16 4/5/2018 18:43 fc -ld

Of course, the European folks can use european date format using -E option.

 fc -lE
2 5.4.2018 18:41 clear
3 5.4.2018 18:42 fc -l
4 5.4.2018 18:42 sudo netctl restart wlp9s0sktab
5 5.4.2018 18:42 ls -l
6 5.4.2018 18:42 pwd
7 5.4.2018 18:42 uname -r
8 5.4.2018 18:43 uname -a
9 5.4.2018 18:43 cat ostechnix.txt
10 5.4.2018 18:43 echo "Welcome to OSTechNix"
11 5.4.2018 18:43 more ostechnix.txt
12 5.4.2018 18:43 wc -l ostechnix.txt
13 5.4.2018 18:43 cat ostechnix.txt
14 5.4.2018 18:43 clear
15 5.4.2018 18:43 fc -l
16 5.4.2018 18:43 fc -ld
17 5.4.2018 18:49 fc -lf

TL;DR

  • When running without any arguments, fc will load the most recent command in the default text editor.
  • When running with a numeric argument, fc loads the editor with the command with that specified number.
  • When running with a string argument, fc loads the most recent command starting with that specified string.
  • When running with two arguments to fc , the arguments specify the beginning and end of a range of commands.

For more details, refer man pages.

$ man fc

And, that’s all for today. Hope you find this article useful. More good stuffs to come. Stay tuned!

Cheers!

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