Linux stuff

Common Commands with examples

These commands and their usage are used for both the LinuC Level 1 Exam 101 and Exam 102. Using these commands in various scenarios to become proficient in basic command-line tasks, file management, and system administration.

ls - List directory contents

The ls command is used to list files and directories in a specified location. It has many options to customize the output.

Examples:

• ls -l: Long listing format, showing permissions, owner, size, and modification date
• ls -a: Show all files, including hidden ones (those starting with a dot)
• ls -R: Recursively list subdirectories
• ls -lh: Use human-readable file sizes (e.g., 1K, 234M, 2G)
• ls /etc: List contents of the /etc directory

cd - Change directory

cd is used to navigate the file system. It can use absolute or relative paths.

Examples:

• cd /home/user: Change to the /home/user directory (absolute path)
• cd ..: Move up one directory level
• cd -: Return to the previous directory
• cd ~: Change to the user's home directory
• cd Documents/Projects: Change to a subdirectory (relative path)

pwd - Print working directory

pwd displays the full path of the current working directory.

Examples:

• pwd: Outputs something like /home/user/Documents
• pwd -P: Print the physical directory, without any symbolic links

mkdir - Create a new directory

mkdir is used to create one or more directories.

Examples:

• mkdir newdir: Create a directory named "newdir"
• mkdir -p parent/child/grandchild: Create nested directories
• mkdir dir1 dir2 dir3: Create multiple directories at once
• mkdir -m 755 secured_dir: Create a directory with specific permissions

touch - Create an empty file or update file timestamps

touch can create empty files or update the access and modification times of existing files.

Examples:

• touch newfile.txt: Create a new empty file or update timestamps if it exists
• touch -t 202502191200 file.txt: Set specific timestamp (YYYYMMDDhhmm)
• touch -r reference_file target_file: Use timestamps from reference_file

cp - Copy files and directories

cp is used to copy files and directories from one location to another.

Examples:

• cp file.txt /home/user/backup/: Copy a file to another directory
• cp -r dir1 dir2: Copy a directory and its contents recursively
• cp -i *.txt /destination/: Copy all .txt files, prompting before overwrite
• cp -p source dest: Preserve file attributes (mode, ownership, timestamps)

mv - Move or rename files and directories

mv can move files/directories or rename them.

Examples:

• mv file.txt newname.txt: Rename a file
• mv /home/user/doc.txt /tmp/: Move a file to another directory
• mv dir1 dir2: Rename a directory (if dir2 doesn't exist) or move dir1 into dir2
• mv -i *.jpg /home/user/Pictures/: Move all .jpg files, prompting before overwrite