Terminal Commands

A curated list of terminal commands for Ubuntu/Linux.

Process Handling

• Kill a process

  • Using process name

    sudo pkill -9 <process_name>

  • Using process ID

    ps aux | grep <process_name> // Get process ID sudo pkill -9 <PID> // Kill process using ID

  • Using parent process (When sometimes killing the process using PID leaves it defunct)

    ps -o ppid=<PID> // Get parent PID sudo pkill -9 <PPID> // Kill process using ID

  • Sometimes, Ctrl + Z is used to kill programs when Ctrl + C fails. However, Ctrl + Z does NOT kill the program but merely sends it to the background of the current terminal. To kill such processes and any other process running in a particular window of the terminal.

    sudo kill jobs -p``

Handle terminal outputs

• Several occasions of compiling a code leaves behind a lot of terminal outputs - errors, warnings and other information. If you’re fed up of scrolling through the terminal to notice each of them, use piping and redirection operators to send the output to files.
• Example ./executable > ~/tmp/output_stored.txt

Debug hardware issues

• Use these commands to discover different hardwares

  • lshw // hardware
  • lspci // PCI devices
  • lsusb // USB buses,
  • lsblk // blocked devices and
  • lsmod // hardware modules plugged into the system

Git command-line interface - Linux Terminal

• Add files to commit

  git add . // Select all files to commit git add <file_name> // Select Particular file to commit git add --all // Select Deletions to commit

• Commit files git commit -m <"commit message">

• Manage files between local and remote repository

  • Get updates from remote repository to local git (Only stored changes, NOT merged into local files) git fetch <branch_name> // Branch specific changes to see from remote git fetch // All remote changes from all branches

  • Push all changes locally committed changes to remote repository git push origin <branch name>

  • Before pushing to remote, pull to local repository (A pull is basically a fetch + merge )
    git pull origin <branch_name>

  • Merge changes from a remote/local branch to local branch git merge <branch_name> // If conflicts come up, resolve manually in local files and commit to remote

• Branch Commands

  • git checkout <branch_name> // Switch to the specified branch
  • git checkout <commit_id> // Switch to a particular commit ID on the current branch
  • git checkout -b <new_branch_name> <base_branch_name>

• Discard/Archive edits

  • git stash // Remove all new unwanted edits
  • git stash list // Obtain the list of stashed or archived changes
  • git stash save "<message_to_save_edit>"
  • git stash apply // Apply last stashed set of changes to edits
  • git stash apply --index // Apply particular stashed changes from the list

• General Commands

  • git init . // Initialize git in a local folder
  • git clone remote_git_url // Clone a remote repository to a local location
  • git status // Check status of repository to see tracked/committed/unco
  • git diff // Check the difference and edits in new uncommitted files
  • git branch // Check the branches available
  • git tag // Check the tags available
  • git reset --hard // Reset the all changes and get to master branch
  • git log // See history for commits, messages and authors
  • git blame <file_name> // List the changes, date and authors for the file

• Configure user credentials

  • Add username for remote git service account git config --global user.name "<github/bitbucket user_name>"

  • Add email ID for remote git service account git config --global user.email "<github/bitbucket user_mail_id>"

  • Connect a local repository to remote git service URL git remote add origin "<github/bitbucket repository URL>"

  • Set the origin/remote git service URL to current local repository git set-url remote origin "<github/bitbucket repository URL>"

Miscellaneous terminal commands

• Terminal content handling
  • clear // Scroll the terminal to clear view - This does NOT erase the terminal history
  • reset // Erase the terminal history and present a clear screen
  • tree // Show the hierachy of existing files in the current folder
  • locate <file_name> // Search the folder location of a file
  • pwd // Print the current working directory
  • history // Get the history of all terminal commands in the window
  • man <terminal_command> // Get the description of the terminal command
  • touch <file_name> // Create

File Management via Terminal

• Handling Files & Directories

  • mkdir -p <path_to_file/file_name> // Create a folder in a specific location
  • mv <file_to_move> <destination> // Move a file to a new location
  • rm <path_to_directory/file_to_remove> // Delete the particular folder/file
  • rm -rf <path_to_directory_to_remove> // Delete with -r flag for recursive and -f for forced (-rf Combined both)
  • cp <file_1> <file_2> // Copy file1 to file2
  • cp -r <directory1> <directory2> // Copy directory1 to directory2 and create the latter if it doesn't exist

• Modifying/Viewing files

  • cat > file_name // Creates a new file in the particular location
  • cat file_name // Displays the content of the file in the terminal
  • cat file_1 file_2 > file_3 // Joins two files (file_1, file_2) and stores the output in a new file file_3
  • more file_name // Display all the contents of the file
  • less file_name // Displays the contents of the file with more [options] (https://en.wikipedia.org/wiki/Less_(Unix))
  • head file_name // Display the first 10 lines of the file
  • tail file_name // Display the last 10 lines of the file
  • tail -f file_name // Display the last 10 lines of a continuously growing in size file

• Viewing the directory contents

  • ls // List files and directories in the current working directory
  • ls -a // List files including the hidden files
  • ls -R // List all the files in the sub directories
  • ls -al // List files with all permissions, size, owner, date of modification etc.

Network Management via Terminal

• ifconfig // Show network information like IP address, HW address and other parameters
• iwconfig // Show wireless information
• iwlist scan // Scan for all wireless networks / Run with sudo, ideally
• sudo /etc/init.d/networking restart // Restart the network configuration - All wireless and wired connections

System Service Management

• start | stop <service> // Start or Stop the particular system service
• status <service> // Check the status of the running service, whether active or not
• etc/init.d/service start | stop | retsart // Toggle a system service
• runlevel // Get current run level

Handling File/Folder Compression

• tar cf <file.tar> < files names| folder> // Compress the list of files or the folder into a tar named file.tar
• tar xf <file.tar> // Extracting the content from file.tar
• tar czf <file.tar.gz> <files> // Create a tar with Gzip compression
• tar xzf <file.tar.gz> // Extract a tar using Gzip
• tar cjf <file.tar.bz2> // Create a tar with Bzip2 compression
• tar xjf <file.tar.bz2> // Extract a tar using Bzip2
• gzip <file> // Compresses file and renames it to file.gz
• gzip -d <file.gz> // Decompresses file.gz back to file

System Info

• date // Display the date on the terminal
• cal // Display the month's calendar on the terminal
• uptime // Show the current uptime for the machine
• w // Display who is online
• whoami // Show the username logged in as, in the current Linux session
• uname -a // Show the kernel information
• df // Show the current disk usage
• du // Show the current directtory space usage
• free // Show the swap and memory usage
• whereis <application> // Search for the possible locations of the application
• which <application> // Show the application which will run by default for the application
• hostname // Displays the current session hostname
• hostname -I // Displays the IP address in the network

Permissions

• chfn // Change real user name and information
• chgrp // Change group ownership for file
• chkconfig // Modify execution of runlevel services
• chmod <options> <permissions> <file_name> // Change access permission for a file(s)
• chown // Change the owner or group for a file
• chroot // Run a command with root credentials
• chsh // Toggle between login shell
• cksum // Perform a CRC checksum for files