Editing Sed (section)

===Other sed commands===
Besides substitution, other forms of simple processing are possible, using some 25 sed commands. For example, the following uses the ''d'' command to filter out lines that only contain spaces, or only contain the end of line character:
<syntaxhighlight lang=bash>
sed '/^ *$/d' inputFileName
</syntaxhighlight>
This example uses some of the following [[regular expression]] [[metacharacter]]s (sed supports the full range of regular expressions):
* The [[caret]] (<code>^</code>) matches the beginning of the line.
* The [[dollar sign]] (<code>$</code>) matches the end of the line.
* The [[asterisk]] (<code>*</code>) matches zero or more occurrences of the previous character.
* The [[Plus and minus signs#Plus sign|plus]] (<code>+</code>) matches one or more occurrence(s) of the previous character.
* The [[question mark]] (<code>?</code>) matches zero or one occurrence of the previous character.
* The [[Full stop|dot]] (<code>.</code>) matches exactly one character.

Complex sed constructs are possible, allowing it to serve as a simple, but highly specialized, [[programming language]]. Flow of control, for example, can be managed by the use of a [[Label (programming language)|label]] (a colon followed by a string) and the branch instruction <code>b</code>, as well as the conditional branch <code>t</code>. An instruction <code>b</code> followed by a valid label name will move processing to the command following that label. The <code>t</code> instruction will only do so if there was a successful substitution since the previous <code>t</code> (or the start of the program, in case of the first <code>t</code> encountered). Additionally, the <code>{</code> instruction starts a [[Block (programming)|subsequence]] of commands (up to the matching <code>}</code>); in most cases, it will be conditioned by an address pattern.