Sed 备忘单

🧾 sed Command Cheatsheet (Stream Editor)

sed is a powerful Unix utility for parsing and transforming text using stream editing.

📌 Basic Syntax

sed [OPTIONS] 'script' [file...] 

• 'script': One or more editing commands.
• [file]: Input file(s). If omitted, sed reads from standard input.

⚙️ Common Options

✂️ Basic Commands

🔍 Substitution Syntax

sed 's/pattern/replacement/flags' file 

Flags

Examples

sed 's/foo/bar/' file # Replace first 'foo' with 'bar' sed 's/foo/bar/g' file # Replace all 'foo' with 'bar' sed 's/foo/bar/2' file # Replace second 'foo' only sed 's/foo/bar/ip' file # Case-insensitive + print 

🗑️ Deletion with sed

sed can delete lines based on line numbers, patterns, or ranges.

🔢 Delete by Line Number

sed '2d' file # Delete line 2 sed '5,10d' file # Delete lines 5 through 10 

🔍 Delete by Pattern

sed '/error/d' file # Delete lines containing 'error' sed '/^$/d' file # Delete blank lines sed '/^#/d' file # Delete comment lines (starting with #) 

🧮 Delete by Range and Pattern

sed '1,/pattern/d' file # Delete from line 1 to first match of 'pattern' sed '/start/,/end/d' file # Delete lines between 'start' and 'end' (inclusive) 

🧠 Conditional Deletion

sed -n '/pattern/!p' file # Print only lines NOT matching 'pattern' 

🧹 Delete Last Line

sed '$d' file # Delete the last line 

📍 Addressing Lines

Line Numbers

sed '2d' file # Delete line 2 sed '3,5p' file # Print lines 3 to 5 

Patterns

sed '/error/d' file # Delete lines containing 'error' sed '/^#/d' file # Delete comment lines 

Combined

sed '1,/pattern/d' file # Delete from line 1 to first match of 'pattern' 

🧪 Advanced Substitution

Using Capture Groups

sed 's/\(foo\)bar/\1baz/' file 

• \(...\) captures a group.
• \1, \2, etc., refer to captured groups.

Escaping Special Characters

sed 's/\/usr\/bin/\/usr\/local\/bin/' file 

Or use alternate delimiter:

sed 's|/usr/bin|/usr/local/bin|' file 

🧨 In-Place Editing

sed -i 's/foo/bar/g' file # Edit file directly sed -i.bak 's/foo/bar/g' file # Backup original as file.bak 

📂 Multiple Commands

Inline

sed -e 's/foo/bar/' -e '/baz/d' file 

Block Syntax

sed ' s/foo/bar/ s/baz/qux/ ' file 

🧵 Append, Insert, Change

sed '/pattern/a\Text to append' file sed '/pattern/i\Text to insert' file sed '/pattern/c\New line content' file 

🔄 Translate Characters

sed 'y/abc/ABC/' file # a→A, b→B, c→C 

🧠 Useful Recipes

Remove Blank Lines

sed '/^$/d' file 

Remove Leading/Trailing Whitespace

sed 's/^[ \t]*//' file # Remove leading sed 's/[ \t]*$//' file # Remove trailing 

Replace Tabs with Spaces

sed 's/\t/ /g' file 

Number Lines

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

📚 Resources

• man sed
• GNU sed manual: https://www.gnu.org/software/sed/manual/sed.html