Sed | Brook

Sed Usage

# Syntax
sed [options] command [input-file]

# With pipeline
cat report.txt | sed 's/Nick/John/g'

Search for text

# Search for a string
sed -n '/hello/p' file.txt
# Case insensitive search
sed -n '/hello/Ip' file.txt
# Only output lines that do not match
sed -n '/hello/!p' file.txt

Change lines

# Insert text before line 5
sed '5i line number five' file.txt
# Insert before lines with "hello"
$ sed '/hello/i Example: ' file.txt
# Delete line 5-7 in file
sed '5,7d' file.txt

Option Example

Option	Example	Description
`-i`	`sed -ibak 's/On/Off/' php.ini`	Backup and modify input file directly
`-E`	`sed -E 's/[0-9]+//g' input-file`	Use extended regular expressions
`-n`	`sed -n '3 p' config.conf`	Suppress default pattern space printing
`-f`	`sed -f script.sed config.conf`	Execute sed script file
`-e`	`sed -e 'command1' -e 'command2' input-file`	Execute multiple sed commands

Commands

Command	Example	Description
`p`	`sed -n '1,4 p' input.txt`	Print lines 1-4
`d`	`sed '1,4 d' input.txt`	Print lines except 1-4
`w`	`sed -n '1,4 w output.txt' input.txt`	Write pattern space to file
`a`	`sed '2 a new-line' input.txt`	Append line after
`i`	`sed '2 i new-line' input.txt`	Insert line before

Sed substitute command and flags

shell

sed 's/original-string/replacement-string/[flags]' [input-file]

Flag	Description	Example
`g`	Global substitution	`sed 's/development/production/g' .env`
`1,2...`	Substitute the nth occurrence	`sed 's/latin1/utf8/2' locale.sql`
`p`	Print only the substituted line	`sed -n 's/error_log = 0/error_log = 1/p' php.ini`
`w`	Write only the substituted line to a file	`sed -n 's/One/Two/w output.txt' words.txt`
`i`	Ignore case while searching	`sed 's/true/FALSE/i' config.php`
`e`	Substitute and execute in the command line	`sed 's/^/ls -l /e' files.list`
`&`	Gets the matched pattern	`sed 's/^.*/<&>/' index.xml`
`( ) \1 \2 \3`	Group using `(` and `)`. Use `\1`, `\2` in replacement to refer the group	`sed 's/([^,]),([^,]),([^,])./\1,\3/g' words.txt`

Sed cheatsheet

Option Example

Commands

Sed substitute command and flags