Basic Usage

Common Commands

`sed 's/old/new/' file.txt`	Replace first occurrence
`sed 's/old/new/g' file.txt`	Replace all occurrences
`sed -i 's/old/new/g' file.txt`	Edit file in-place
`sed -n '5p' file.txt`	Print line 5
`sed '5d' file.txt`	Delete line 5
`sed '/pattern/d' file.txt`	Delete matching lines

Substitution

Patterns

# Replace all (global)
sed 's/foo/bar/g' file.txt

# Case-insensitive
sed 's/foo/bar/gi' file.txt

# Different delimiters
sed 's|/old/path|/new/path|g' file.txt

# Backreference
sed 's/\(.*\)/prefix_\1/' file.txt

Addressing

Line Selection

Line numbers

sed '5s/old/new/' file.txt     # Line 5 only
sed '1,5s/old/new/g' file.txt  # Lines 1-5
sed '5,$s/old/new/g' file.txt  # Line 5 to end
sed '/pattern/s/old/new/' file.txt  # Matching lines

Examples

Common Tasks

Useful examples

# Remove trailing whitespace
sed 's/[[:space:]]*$//' file.txt

# Remove blank lines
sed '/^$/d' file.txt

# Remove HTML tags
sed 's/<[^>]*>//g' file.html

# Number lines
sed = file.txt | sed 'N;s/\n/\t/'