Master Essential Linux Commands: From Navigation to File Management

1. Common Commands

1.1 Directory Operations

ls – list directory contents.

Command: ls [options] [file|directory] Options: -a – show all files --color=when – color output (default always) -d – list directory entries themselves -h – human‑readable sizes -i – show inode number -l – long format # ls -l cd – change the current directory.

Command: cd [directory] Special symbols: ~ – home directory - – previous directory . – current directory .. – parent directory

pwd – print working directory.

Command:

pwd

1.2 File Operations

touch – create an empty file or update timestamps.

Command: touch filename stat – display detailed file status.

Command: stat filename cat – concatenate files and print to standard output.

Command:

cat [options] filename

-A

– show all hidden symbols -E – display end‑of‑line characters -n – number lines -T – show tabs as ^I -v – display non‑printing characters

more – page through a file.

Command: more filename Controls: Space (next page), b (previous page), Enter (next line), /string (search), q (quit).

less – similar to more but allows backward movement.

Command: less filename head – display the beginning of a file.

Command: head -n N filename tail – display the end of a file.

Command:

tail -n N filename

1.3 Directory and File Commands

mkdir – create a directory.

Command: mkdir [-p] directory rmdir – remove an empty directory.

Command: rmdir directory rm – remove files or directories.

Command: rm [-r] [-f] [-i] file|directory cp – copy files or directories.

Command: cp [-a] [-d] [-i] [-p] [-r] source destination mv – move or rename files/directories.

Command:

mv [-f] [-d] [-v] source destination

2. Permission Management

chmod – change file mode (permissions).

Command:

chmod [options] mode file

-R

– recursive

Permission syntax: [ugoa][+-=][rwx] (e.g., u+r).

Numeric mode: 4 = read, 2 = write, 1 = execute.

chown – change file owner and group.

Command:

chown [options] owner[:group] file

-R

– recursive

chgrp – change group ownership.

Command:

chgrp [options] group file

3. Help Commands

man – display manual pages.

Command:

man [options] command

-f

– show help level -k – search related help topics

info – view GNU info documentation.

help – show built‑in shell command help.

--help – display command‑specific help.

4. Search Commands

whereis – locate binary, source, and manual files.

Command: whereis name which – show the full path of an executable.

Command: which name locate – find files by name using a database.

Command: locate pattern find – search for files in a directory hierarchy.

Command:

find path [options] expression

-name

/ -iname – name match (case‑insensitive) -size [+|-]N – size criteria -atime / -mtime / -ctime – time criteria -perm – permission criteria -uid / -gid / -user / -group – owner/group -type d|f|l – file type -a, -o, -not – logical operators -exec – execute a command on found files -ok – like -exec but asks for confirmation

grep – search text using patterns.

Command:

grep [options] "pattern" file

-i

– ignore case -n – show line numbers -v – invert match --color=auto – highlight matches

Pipe (|) – pass output of one command as input to another.

5. Compression Commands

zip – package and compress files.

Command: zip [-r] archive.zip files unzip – extract zip archives.

Command: unzip [-d target_dir] archive.zip gzip – compress files using LZ77.

Command: gzip [-c] [-d] [-r] file gunzip – decompress gzip files (alias for gzip -d).

Command: gunzip file.gz tar – archive files; with -z or -j for compression.

Create archive: tar -cvf archive.tar files Extract archive: tar -xvf archive.tar Compressed with gzip: tar -zcvf archive.tar.gz files Compressed with bzip2:

tar -jcvf archive.tar.bz2 files

6. Shutdown and Reboot

sync – flush file system buffers.

Command: sync shutdown – schedule system halt or reboot.

Command:

shutdown [-h|-r] [+time] ["message"]

-c

– cancel a pending shutdown -h – halt -r – reboot

reboot – immediate reboot.

Command: reboot halt / poweroff – immediate power‑off (not recommended for graceful shutdown).

Command: halt or poweroff init – change runlevel (e.g., init 0 to halt, init 6 to reboot).

Command:

init [runlevel]