The history functionality in the Linux Command-Line Interface (CLI) allows users to access previously executed commands, providing a convenient way to avoid re-typing the same instructions over and over again. This article aims to delve deep into the concept of command history in the Linux CLI, explaining its various aspects, keystroke combinations, and examples to put it into practice.
Why Is Command History Important?
- Efficiency: Quickly recall and reuse previously executed commands.
- Troubleshooting: Review the command history to understand past actions and diagnose issues.
- Learning: New users can refer to the history to recall how certain tasks were accomplished.
Mechanisms Behind Command History
Many Linux shells, like Bash, use the GNU Readline library to handle command history. This library maintains a history list and provides a host of features for interacting with that list.
Keystroke Combinations for Using History
Here is a table detailing the keystrokes involved in navigating and using the command history in Linux CLI:
|Go to the previous command in history.
|Go to the next command in history.
Ctrl + R
|Reverse search through command history.
Ctrl + S
|Forward search through command history (may be disabled on some systems).
Ctrl + P
|Go to the previous command in history (same as
Ctrl + N
|Go to the next command in history (same as
Ctrl + O
|Execute the current command found in history and move to the next one.
|Execute the last command.
|Execute the N-th command in history.
|Execute the command N positions back.
|Execute the most recent command that starts with 'string'.
|Execute the most recent command containing 'string'.
Ctrl + U
|Clear the line before the cursor.
Ctrl + K
|Clear the line after the cursor.
Let's see how to effectively use the history functionality with some examples.
For demonstration purposes, we'll assume you've created a folder
demo_history with some dummy files and folders.
Creating Dummy Files and Directories
touch file_a.txt file_b.txt
Example 1: Using Up and Down Arrows
After running a couple of commands, you can press the
Up Arrow to cycle
backward through your command history and the
Down Arrow to cycle forward.
Up Arrow twice to go back to the
Example 2: Using Reverse Search
Ctrl + R and start typing a part of a command you've previously run, for
Enter to execute the found command again.
Example 3: Using
!! to Repeat Last Command
Let's say the last command you ran was:
To rerun this command, simply type
!! and press
Example 4: Using
!N to Execute a Specific Command
You can use the
history command to display the list of previously executed
commands along with their numbers. To run a specific command number
N, you can
!N. For example, to run the 5th command in your history:
Example 5: Using
!string to Execute Commands That Start with a String
If you want to rerun the last command that started with the string "ls", you can
The history functionality in Linux CLI is a powerful feature that greatly enhances efficiency and productivity. By becoming proficient in navigating and leveraging the command history, you can perform tasks more quickly and accurately, improving your overall experience with the Linux command line.
What Can You Do Next 🙏😊
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