System Administration

SED Command Cheatsheet

Comprehensive guide to SED (Stream Editor) covering command syntax, options, commands, flags, address patterns, regular expressions, and practical examples for powerful text manipulation and automation.

Essential for VPS server administrators, DevOps engineers, and Linux users who need to automate text processing tasks on their servers.

#sed #text-processing #stream-editor #linux #regex #sysadmin
Sign In to Download

Free account required

$

SED Syntax

$ sed [options] 'command' file

SED (Stream Editor) is a powerful text processing tool essential for Linux server administration and log file analysis. Perfect for processing configuration files and automating text transformations.

Options
Flags like -n, -i, -e
Command
Actions like s, d, p, a, i
File
Target file to process

Related Cheatsheets

→ Grep Command → Linux Log Parsing → Linux Commands → Linux Redirections

Table of Contents

1. SED Options 2. SED Commands 3. SED Flags 4. Address Patterns 5. Regex Metacharacters 6. Common Examples

SED Options

Option Description Example
-n Suppress automatic printing of pattern space $ sed -n '/banana/p' data.txt
-i Edit file in-place (backup created if extension provided) $ sed -i 's/banana/orange/' data.txt
-e Execute multiple sed commands $ sed -e 'command1' -e 'command2' input-file
-f Read sed commands from a script file $ sed -f script.sed data.txt
-r or -E Use extended regular expressions $ sed -E 's/(word1|word2)/match/' file.txt

SED Commands

Command Description Example
d Delete the current pattern space (line) $ echo "Hello, World!" | sed 's/World!/World/'
s Used for substitution $ echo "Hello, World!" | sed 's/World!/Universe/'
i Insert text before the current line $ echo "Hello!" | sed 'i Hello'
a Append text after the current line $ echo "Hello." | sed 'a World!'
r Append a read from a file $ echo "Hello." | sed 'r additional.txt'
c Change (replace) text $ echo "Hello, World!" | sed 'c Goodbye'
p Print the current pattern space $ sed -n '/pattern/p' file.txt
q Quit the sed command at the specified point $ sed '2q' data.txt
y Transform characters (like tr command) $ echo "hello" | sed 'y/helo/HELO/'
n Read next input line $ sed 'n;d' file.txt

SED Flags (for substitution command)

Flag Description Example
g Globally replace all occurrences of a pattern in the current line $ echo "Hello, hello, hello!" | sed 's/hello/Hi/g'
p Print only the substituted line (use with -n) $ sed -n 's/pattern/&/p' data.txt
d Delete the pattern space (current line) $ sed '/pattern/d' file.txt
i Case-insensitive matching $ sed 's/hello/Hi/i' file.txt
w Write the pattern space to a file $ sed -n 's/pattern/&/w output.txt' data.txt
1,2,3... Replace the Nth occurrence only $ echo "hello hello hello" | sed 's/hello/Hi/2'

Address Patterns

Addresses specify which lines the sed command should act upon. You can use line numbers, patterns, or ranges.

Single Line Number

$ sed '3d' file.txt          # Delete line 3

Line Range

$ sed '2,5d' file.txt        # Delete lines 2 to 5
$ sed '2,5p' file.txt        # Print lines 2 to 5

Pattern Matching

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

Pattern Range

$ sed '/start/,/end/d' file.txt  # Delete from start to end pattern

Last Line

$ sed '$d' file.txt          # Delete last line
$ sed '$p' file.txt          # Print last line

Negation (NOT)

$ sed '/pattern/!d' file.txt # Delete lines NOT matching pattern

Regex Metacharacters

Metacharacter Description
. Match any character except new line
? Match 0 or one characters
* Match 0 or more characters
+ Match 1 or more characters
^ Beginning of line
$ End of line
[abc] Match any character in the set (a, b, or c)
[^abc] Match any character NOT in the set
| Alternation (OR operator)
\< Start of word
\> End of word
\( \) Group expressions (backreferences)
\n Backreference (nth captured group)

Common Examples

Replace Text (Basic Substitution)

$ sed 's/old/new/' file.txt              # Replace first occurrence per line
$ sed 's/old/new/g' file.txt             # Replace all occurrences

Delete Lines

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

Tip: Combine SED with grep for powerful log analysis workflows.

Print Specific Lines

$ sed -n '5p' file.txt                   # Print line 5
$ sed -n '10,20p' file.txt               # Print lines 10 to 20
$ sed -n '/pattern/p' file.txt           # Print lines matching pattern

Multiple Commands

$ sed -e 's/foo/bar/' -e 's/baz/qux/' file.txt
$ sed 's/foo/bar/; s/baz/qux/' file.txt

In-Place Editing

$ sed -i 's/old/new/g' file.txt          # Edit file directly (Linux)
$ sed -i.bak 's/old/new/g' file.txt      # Create backup with .bak extension

Insert and Append Text

$ sed '3i\New line here' file.txt        # Insert before line 3
$ sed '3a\New line here' file.txt        # Append after line 3

Backreferences (Capture Groups)

$ sed 's/\(.*\)@\(.*\)/\2 - \1/' emails.txt  # Swap email parts
$ sed 's/\([0-9]\{3\}\)-\([0-9]\{4\}\)/(\1) \2/' phone.txt

Case Conversion (GNU sed)

$ sed 's/.*/\U&/' file.txt               # Convert to uppercase
$ sed 's/.*/\L&/' file.txt               # Convert to lowercase

Remove Leading/Trailing Whitespace

$ sed 's/^[ \t]*//' file.txt             # Remove leading whitespace
$ sed 's/[ \t]*$//' file.txt             # Remove trailing whitespace
$ sed 's/^[ \t]*//; s/[ \t]*$//' file.txt  # Remove both

Number Lines

$ sed '=' file.txt | sed 'N;s/\n/\t/'     # Add line numbers

Resources

VPS Hosting

Company

Legal

Back to Cheatsheets

Master Text Processing & Automation

Need powerful servers for log analysis and text processing? Check out our VPS benchmarks to find the perfect hosting provider with optimal CPU and disk performance.

View VPS Benchmarks Free Server Tools More Cheatsheets