sed d: Delete Lines from a Stream

sed d removes lines from the output, selected by line number, range, or a regex address.

Deleting is the inverse of printing. Pair the d command with an address and sed drops exactly the lines you name.

What it does

The d command deletes the current line so it never reaches output. With no address it deletes every line; with an address it deletes only the matching lines. d ends processing of that line, so commands after it do not run on deleted lines.

Common usage

Terminal

sed '3d' file              # delete line 3
sed '2,5d' file            # delete lines 2 through 5
sed '/^#/d' config.ini     # delete comment lines
sed '/^$/d' file           # delete blank lines
sed '$d' file              # delete the last line

Options

Address	What it deletes
Nd	The single line number N
M,Nd	Lines M through N inclusive
/regex/d	Every line matching the regex
$d	The last line of input
/a/,/b/d	From the first line matching a to the next matching b
Nd with -n	Has no extra effect; d already suppresses the line

In CI

Deleting comment and blank lines is a common way to normalize a config before a diff or checksum. The d syntax is identical on GNU and BSD sed, so deletes are safe in cross-platform jobs as long as the address regex itself is portable.

Common errors in CI

sed: -e expression #1, char N: unexpected ,' means a malformed range such as ,5d with no start. sed: -e expression #1, char N: unknown command: d' can appear if a stray character precedes d, for example a missing slash on the address making sed read the pattern as a command.