Linux Basics

Sed

Replace the first occurrence of a string in a file, and print the result

sed 's/find/replace/' filename

Replace all the occurrences of a string in a file, and print the result

sed 's/find/replace/g' filename

Replace all occurrences of an extended regular expression in a file

sed -E 's/regular_expression/replace/g' filename

Replace in place all the occurrences of a string in a file and overwrite the file

sed -i '' 's/find/replace/g' filename

Add prefix to all files

sed -i '1s/^/# Copyright (c) MIT License\n\n/' *

Replace only on lines matching the line pattern

sed '/line_pattern/s/find/replace/' filename

Print only text between n-th line till the next empty line:

sed -n 'line_number,/^$/p' filename

Apply multiple find-replace expressions to a file:

sed -e 's/find/replace/' -e 's/find/replace/' filename

Replace separator / by any other character not used in the find/replace patterns, e.g. ;

sed 's;find;replace;' filename
sed '\;deleteme;d' filename

Replacing Newlines with sed

sed ':a;N;$!ba;s/\n//g' filename

Delete the line at the specific line number in a file:

• Any line number: sed '<line_number>d' filename

• First line: sed '1d' filename

• Last line: sed '$d' filename

• Multiple lines: sed '1d;3d;5d' filename

• Exclude lines: sed '1,3!d' filename

• Delete empty lines in a file: sed '/^$/d’ filename