How to match whitespace in sed

sedwhitespace

How can I match whitespace in sed? In my data I want to match all of 3+ subsequent whitespace characters (tab space) and replace them by 2 spaces. How can this be done?

Best Answer

The character class \s will match the whitespace characters <tab> and <space>.

For example:

$ sed -e "s/\s\{3,\}/  /g" inputFile

will substitute every sequence of at least 3 whitespaces with two spaces.

REMARK: For POSIX compliance, use the character class [[:space:]] instead of \s, since the latter is a GNU sed extension. See the POSIX specifications for sed and BREs

Related Solutions

Sed to remove all whitespace from a line

You should use the g (global) flag, which makes sed act on all matches of the pattern on each line, rather than the first match on each line:

sed 's/ //g' test.txt > test2.txt

Sed parsing data: fields (words) separated with whitespace

A trivial example in awk to suggest what can be done

awk '{print $2 $1 $3}` < input_file.txt

simply rearranges the first two fields while printing all three on all lines.

To rearrange those lines have exactly three fields, preserve any that start with # (i.e. comment in sh-like languages) and delete all others

awk `/^#/{print $0;next} NF==3{print $2 $1 $3;next} {}' < input_file.txt

Most unix systems have a fairly complete awk man-page.

The important this for your purposes here is that the fields are accessibly with $1, $2, ..., where "field" is defined as strings of stuff separated by FS (i.e. the field separator) which defaults to (a space).

Best Answer

Related Solutions

Sed to remove all whitespace from a line

Sed parsing data: fields (words) separated with whitespace

Related Question