[Sed] Delete one or more lines from a file

Removing one (or several) line (s) of a file


Syntax:

sed '{[/]<n>|<string>|<regex>[/]}d' <fileName>
sed '{[/]<adr1>[,<adr2>][/]d' <fileName>

• /.../=delimiters
• n = line number
• string = string found in in line
• regex = regular expression corresponding to the searched pattern
• addr = address of a line (number or pattern )
• d = delete

Examples

Remove the 3rd line:

sed '3d' fileName.txt

Removal of the line containing the string "awk":

sed '/awk/d' filename.txt

Remove the last line:

sed '$d' filename.txt

Remove all empty lines:

sed '/^$/d' filename.txt
sed '/./!d' filename.txt

Remove line "matched" by a regular expression (by eliminating one containing digital characters (at least 1 digit) located at the end of the line).

sed '/[0-9/][0-9]*$/d' filename.txt

Removing the interval between lines 7 and 9.

sed '7,9d' filename.txt 

Same operation but replacing the address by "parameters".

sed '/-Start/,/-End/d' filename.txt

The above examples are only change at the display of the file (stdout1= screen).

For permanent changes to the old versions (<4) use a temporary file for GNU sed use the "-i[suffix]":

sed -i".bak" '3d' filename.txt