Essential Linux Commands Every Developer Should Master

Basic Navigation Commands

cd – Change Directory cd .. Return to the parent directory cd . Enter the current directory (no effect) cd - Return to the previous directory (not necessarily the parent)

Listing Files and Directories

ls – List Files

Usage: ls [options] [file] Common options: ls -l Show permissions and attributes ls -a List all files, including hidden ones ls -h Display sizes in human‑readable format (GB, kB, etc.) ls -al Combine -a and

-l

Viewing Detailed File Information

stat – Show File Details

Displays permissions, attributes, size, modification time, access time, and more—more detailed than ls -l.

Usage:

stat filename

Searching Text Within Files

grep – Text Search/Filter

Usage: grep [options] pattern [file] (often combined with pipes)

Common options: -i Case‑insensitive search -v Invert match (show lines that do NOT contain the pattern) -c Count matching lines -n Show line numbers

Finding Files

find – Locate Files

Usage: find [PATH] [options] [-print] Key options: -name filename Find files by name -perm Search by permission bits -user username Search by file owner -group groupname Search by group -mtime -n / -mtime +n Modified within n days or older than n days -ctime -n / -ctime +n Created within n days or older than n days -size +-n[c] File size greater or less than n blocks/bytes

Examples:

Find all .log files under /tmp:

Find files in /proc with permission 777 and containing "root":

Find files created by user root under /tmp:

Find files in /tmp modified within the last day:

Find files smaller than 72 bytes in /tmp:

Process Management

ps – Snapshot of Processes

Shows currently running processes and their status; does not update continuously.

top – Real‑Time Process Monitor

Continuously displays CPU, memory, and load usage per process.

Common options: -d seconds Refresh interval -i Hide idle or zombie processes -n NUM Number of updates before exiting -p PID Monitor a specific PID -H -p PID Show threads of a process

Killing Processes

kill – Terminate by PID

Usage: kill [-signal] PID (default signal is TERM; -9 forces termination)

killall – Terminate by Name

Usage: killall process_name kills all processes matching the name.

Other Useful Commands

pwd – Print Working Directory

Displays the current directory path.

help / man – Command Help

Use command --help or man command to view usage information.