Linux CheatSheet

Cheatsheet of commands to use when working on Linux-based systems. Here the commands that I use most frequently.

Submissions or issues identified can be submitted via issue on this project's repository.

These commands have been tested and confirmed to work on Ubuntu-based systems. They also should, but are not guaranteed to work on Debian-based and Linux-based systems.

List All Files in Current Directory

ls -al

List All Files in Current Directory in Reverse Order

ls -altr

List Files in Current Directory and Filter with Grep

ls -al | grep -i <searchString>

List the directory contents. Then search for the searchString in the output of the directory listing. NOTE: Depending on the system, the searchString may be highlighted in a different color when it is found.

Bash

View Command Execution History

history

Output:

almostengineer@aeoffice$ history
2016  cd ../..
2017  mkdocs build 
2018  history | grep serve 
2019  mkdocs serve > /dev/null 2>&1 &  
2020  git status 
2021  history

The first column shows the command number and the second column will show the command that was run.

Run Command From History

!<number>

Will run the command from your history as it was originally typed. You will need to replace <number> with the number that shows in the output. For example, entering in !2020 after running the history command above will give the below output.

Output:

almostengineer@aeoffice$ !2020
git status 
On branch master
Your branch is ahead of 'origin/master' by 2 commits.
  (use "git push" to publish your local commits)

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   docs/resources/linux-cheatsheet.md

no changes added to commit (use "git add" and/or "git commit -a")

Sending Emails

Email A File To User

uuencode <filename> <filename> | mailx -s <subject> <to>

The <filename> does have to be typed twice. First time is the name of the file on the file system. The second time is what you want the name of the attachment to be. <subject> is the subject of the email. <to> is who the email should be sent to.

System Maintenance

Remove Old Linux Kernels (Ubuntu and Debian Based Systems)

apt-get autoremove --purge $(dpkg --list | egrep -i --color 'linux-image|linux-headers' | grep -v $(uname -r)^C awk '/ii/{ print $2}')