General Commands

Directory listing and file information commands

# List files and directories
ls

# List with details
ls -l

# List all files (including hidden)
ls -a

# List with human-readable sizes
ls -lh

# List with recursive directory tree
ls -R

# List with color output
ls --color=auto

# List with specific pattern
ls *.txt

# List with sort by size
ls -lS

# List with sort by time
ls -lt

# List with reverse sort
ls -lr

Directory navigation and current location commands

# Change to home directory
cd

# Change to specific directory
cd /path/to/directory

# Change to parent directory
cd ..

# Change to root directory
cd /

# Change to previous directory
cd -

# Show current directory
pwd

# Change to directory and list contents
cd /path && ls -la

# Change to directory with tilde expansion
cd ~/Documents

File copying, moving, and deletion operations

# Copy file
cp source.txt destination.txt

# Copy directory recursively
cp -r source_dir destination_dir

# Copy with preserve attributes
cp -p source.txt destination.txt

# Copy with verbose output
cp -v source.txt destination.txt

# Move/rename file
mv old_name.txt new_name.txt

# Move file to directory
mv file.txt /path/to/directory/

# Remove file
rm file.txt

# Remove directory recursively
rm -rf directory_name

# Remove with confirmation
rm -i file.txt

# Remove with verbose output
rm -v file.txt

Directory creation and removal operations

# Create directory
mkdir new_directory

# Create multiple directories
mkdir dir1 dir2 dir3

# Create directory with parents
mkdir -p path/to/directory

# Create directory with specific permissions
mkdir -m 755 new_directory

# Remove empty directory
rmdir empty_directory

# Remove multiple empty directories
rmdir dir1 dir2 dir3

# Remove directory tree
rm -rf directory_tree

File permissions and ownership management

# Change file permissions (numeric)
chmod 755 file.txt

# Change file permissions (symbolic)
chmod u+x file.txt
chmod g-w file.txt
chmod o+r file.txt

# Change permissions recursively
chmod -R 755 directory/

# Change file ownership
chown user:group file.txt

# Change ownership recursively
chown -R user:group directory/

# Change only user ownership
chown user file.txt

# Change only group ownership
chgrp group file.txt

File and directory search operations

# Find files by name
find /path -name "*.txt"

# Find files by type
find /path -type f

# Find directories
find /path -type d

# Find files by size
find /path -size +100M

# Find files by modification time
find /path -mtime -7

# Find files by user
find /path -user username

# Find files and execute command
find /path -name "*.txt" -exec ls -l {} \;

# Find files and delete
find /path -name "*.tmp" -delete

# Find files with case-insensitive search
find /path -iname "*.TXT"

Text search and pattern matching in files

# Search for text in files
grep "pattern" file.txt

# Search recursively
grep -r "pattern" /path/

# Search with case-insensitive
grep -i "pattern" file.txt

# Search with line numbers
grep -n "pattern" file.txt

# Search with context lines
grep -A 3 -B 3 "pattern" file.txt

# Search for whole words only
grep -w "pattern" file.txt

# Search with regular expressions
grep -E "pattern1|pattern2" file.txt

# Search and show only filenames
grep -l "pattern" *.txt

# Search and invert match
grep -v "pattern" file.txt

Stream editing and text transformation operations

# Replace text in file
sed 's/old/new/g' file.txt

# Replace text in place
sed -i 's/old/new/g' file.txt

# Delete lines containing pattern
sed '/pattern/d' file.txt

# Print specific lines
sed -n '10,20p' file.txt

# Add text to beginning of line
sed 's/^/prefix /' file.txt

# Add text to end of line
sed 's/$/ suffix/' file.txt

# Delete empty lines
sed '/^$/d' file.txt

# Multiple substitutions
sed -e 's/old1/new1/g' -e 's/old2/new2/g' file.txt

Advanced text processing and data manipulation

# Print specific columns
awk '{print $1, $3}' file.txt

# Print lines matching pattern
awk '/pattern/ {print}' file.txt

# Print with custom field separator
awk -F',' '{print $1, $2}' file.csv

# Calculate sum of column
awk '{sum += $1} END {print sum}' file.txt

# Print with line numbers
awk '{print NR, $0}' file.txt

# Print lines with specific length
awk 'length($0) > 50' file.txt

# Print unique values
awk '{print $1}' file.txt | sort | uniq

# Print with conditions
awk '$3 > 100 {print $1, $3}' file.txt

Data sorting and duplicate removal operations

# Sort file alphabetically
sort file.txt

# Sort numerically
sort -n numbers.txt

# Sort in reverse order
sort -r file.txt

# Sort by specific column
sort -k2 file.txt

# Sort and remove duplicates
sort file.txt | uniq

# Count unique lines
sort file.txt | uniq -c

# Show only unique lines
sort file.txt | uniq -u

# Show only duplicate lines
sort file.txt | uniq -d

# Sort with case-insensitive
sort -f file.txt