sed Command Guide

sed 'command' filename

echo "hello world" | sed 's/world/universe/'

# Replace first occurrence on each line
sed 's/old/new/' file.txt

# Replace all occurrences on each line
sed 's/old/new/g' file.txt

sed 's/error/warning/gi' file.txt

# Replace only the 2nd occurrence
sed 's/the/THE/2' file.txt

# Edit file in place (GNU sed)
sed -i 's/old/new/g' file.txt

# Create backup before editing
sed -i.bak 's/old/new/g' file.txt

# macOS sed requires empty string for no backup
sed -i '' 's/old/new/g' file.txt

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

# Delete specific line number
sed '5d' file.txt

# Delete range of lines
sed '5,10d' file.txt

# Delete from line 5 to end
sed '5,$d' file.txt

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

# Print only matching lines (-n suppresses default output)
sed -n '/pattern/p' file.txt

# Print specific line
sed -n '5p' file.txt

# Print range of lines
sed -n '5,10p' file.txt

# Print lines between two patterns
sed -n '/start/,/end/p' file.txt

# Apply to line 3
sed '3s/old/new/' file.txt

# Apply to lines 3-7
sed '3,7s/old/new/' file.txt

# Apply from line 5 to end
sed '5,$s/old/new/' file.txt

# Apply to lines matching pattern
sed '/error/s/old/new/' file.txt

# Apply to lines NOT matching pattern
sed '/pattern/!s/old/new/' file.txt

# Match word boundaries
sed 's/\bword\b/replacement/g' file.txt

# Use extended regex (-E or -r)
sed -E 's/[0-9]+/NUMBER/g' file.txt

# Capture groups
sed -E 's/([0-9]+)-([0-9]+)/\2-\1/g' file.txt

# Match beginning/end of line
sed 's/^/PREFIX: /' file.txt
sed 's/$/ :SUFFIX/' file.txt

sed 's/<[^>]*>//g' file.html

sed 's/\r$//' file.txt

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

sed -n 's/.*\([a-zA-Z0-9._-]*@[a-zA-Z0-9._-]*\).*/\1/p' file.txt

sed '/DEBUG/s/^/# /' config.txt

sed -i 's/old/new/g' *.txt

# Using -e flag
sed -e 's/foo/bar/' -e 's/baz/qux/' file.txt

# Using semicolons
sed 's/foo/bar/; s/baz/qux/' file.txt

# Using newlines (in a script)
sed '
  s/foo/bar/
  s/baz/qux/
  /delete/d
' file.txt