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This article introduces you to Linux beginners to share fc examples, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Fc (short for Fix Commands) is a shell built-in command that lists, edits, and executes recently entered commands in an interactive shell. You can edit the most recent commands with your favorite editor and execute them again without having to type them all over again. In addition to avoiding repeated typing of long and complex commands, it is also useful for correcting spelling mistakes. Because it is a shell built-in command, most shell includes it, such as Bash, Zsh, Ksh, and so on. In this short article, let's learn how to use the fc command in Linux.

The fc commands tutorial and examples list the most recently executed commands

Execute the fc-l command with no other arguments, which lists the last 16 commands.

$fc-l507 fish508 fc-l509 sudo netctl restart wlp9s0sktab510 ls-1511 pwd512 uname-r513 uname-a514 touch ostechnix.txt515 vi ostechnix.txt516 echo "Welcome to OSTechNix" 517 sudo apcman-Syu518 sudo pacman-Syu519 more ostechnix.txt520 wc-l ostechnix.txt521 cat ostechnix.txt522 clear

The-r option is used to reverse sort the output.

$fc-lr

The-n option is used to hide line numbers.

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

In this way, the line number is no longer displayed.

If you want to start with a command, simply add a line number after the-l option. For example, to display line number 520 to the most recent command, you can do this:

$fc-l 520520 ls-l521 pwd522 uname-r523 uname-a524 echo "Welcome to OSTechNix" 525 sudo apcman-Syu526 cat ostechnix.txt527 wc-l ostechnix.txt528 more ostechnix.txt529 clear530 fc-ln531 fc-l

To list a range of commands, use the beginning and end line numbers as arguments to fc-l, such as 520 to 525:

$fc-l 520 525520 ls-l521 pwd522 uname-r523 uname-a524 echo "Welcome to OSTechNix" 525 sudo apcman-Syu

In addition to using line numbers, we can also use characters. For example, to list all commands from the most recent pwd to the most recent command, simply use the starting letter as follows:

$fc-l p521 pwd522 uname-r523 uname-a524 echo "Welcome to OSTechNix" 525 sudo apcman-Syu526 cat ostechnix.txt527 wc-l ostechnix.txt528 more ostechnix.txt529 clear530 fc-ln531 fc-l532 fc-l 520533 fc-l 520 525534 fc-l 520535 fc-l 522536 fc-l

To list all commands between pwd and more, you can use the starting letter, like this:

$fc-l p m

Alternatively, use the first letter of the start command and the line number of the end command:

$fc-l p 528

Or both use line numbers:

$fc-l 521 528

All three commands show the same result.

Edit and execute the previous command

We often type the wrong command, and you can use the default editor to correct the spelling mistake and execute it without typing the command again.

Edit and execute the previous command:

$fc

This loads the last command in the default editor.

As you can see, my last order was fc-l. You can modify it at will, and it will be executed automatically when you save and exit the editor. This is useful when commands or parameters are long and complex. It is important to note that it can also be devastating. For example, if your last command was a dangerous rm-fr, you may lose your important data when it is automatically executed. So be careful with every order.

Change the default editor

Another useful option is-e, which can be used to select a different editor for the fc command. For example, if we want to use nano to edit the last command:

$fc-e nano

This command opens the nano editor (instead of the default editor) to edit the previous command.

If you find the-e option too troublesome, you can modify your default editor by setting the environment variable FCEDIT to the name of the editor you want fc to use.

For example, to set nano as the default editor, edit your ~ / .profile or other initialization files: (LCTT translation note: if ~ / .profile does not exist, you can create it yourself; if you are using bash, you can edit ~ / .bash_profile)

$vi ~ / .profile

Add the following line:

FCEDIT=nano# LCTT translation note: if fc is used in a child shell, * export FCEDIT here

You can also use the full path of the editor:

FCEDIT=/usr/local/bin/emacs

Enter: wq save exit. For the changes to take effect immediately, run the following command:

$source ~ / .profile

Now you can use the nano editor to edit the previous command by typing fc.

Execute the previous command directly without editing

We now know that the fc command loads the last command into the editor without any arguments. But sometimes you may not want to edit, just want to execute the last command again. This is simple, just add a hyphen (-) at the end:

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

As you can see, fc takes the-e option, but does not edit the previous command (echo "Welcome to OSTechNix" in the example).

It is important to note that some options are only valid for the specified shell. For example, the following options can be used in zsh, but not in Bash or Ksh.

Displays the execution time of the command

To know when the command was executed, you can use the-d option:

Fc-ld1 18:41 exit2 18:41 clear3 18:42 fc-L4 18:42 sudo netctl restart wlp9s0sktab5 18:42 ls-L6 18:42 pwd7 18:42 uname-R8 18exit2 43 uname-a9 18 echo "Welcome to OSTechNix" 11 1843 more ostechnix.txt12 18exit2 43 wc-l ostechnix.txt13 1843 cat ostechnix.txt14 1843 clear15 1843 fc-l

This way you can check the specific execution time of the most recent command.

Using the option-f, you can display the full timestamp for each command.

Fc-lf 14 Grammer 18:41 exit 2 4 Uniqpare 2018 18:41 clear 3 4 pwd 5 4 pwd 2018 18:42 fc-l 4 Grey 531 18:42 sudo netctl restart wlp9s0sktab 5 4 ls-l 6 4 Grammer 2018 18:42 pwd 7 4 pwd 52018 18:42 uname-r 8 4 pwd 54 pwd 2018 1843 echo uname-a 9 4 prune 52018 1843 echo-a 9 4 peg 52018 1843 echo 10 4 OSTechNix "11 4 cat ostechnix.txt" 11 4 fc 2018 18:43 more ostechnix.txt 12 4 fc 5 Grammer 2018 18:43 wc-l ostechnix.txt 13 4 Gramps 2018 18:43 cat ostechnix.txt 14 5 fc "11 4 fc" 2018 18:43 fc 15 4 fc-l 16 4 fc-1 16 4 fc-ld

Of course, fellow villagers in Europe can also use the-E option to display the European time format.

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 1843 cat ostechnix.txt 10 5.4.2018 1818 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-lffc usage summary

When there are no parameters, fc loads the last command into the default editor.

When taking a number as an argument, fc loads the command specified by the number into the default editor.

When taking a character as an argument, fc loads the most recent command that begins with the specified character into the default editor.

When there are two parameters, they specify the start and end of the range of commands that need to be listed.

Please refer to the man manual for more details.

This is the end of man fc's fc sample sharing for Linux beginners. I hope the above content can be of some help and learn more knowledge. If you think the article is good, you can share it for more people to see.

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