Using Sed to parse and change text.

FILE SPACING:

# double space a file

sed G

# double space a file which already has blank lines in it. Output file

# should contain no more than one blank line between lines of text.

sed ‘/^$/d;G’

# triple space a file

sed ‘G;G’

# undo double-spacing (assumes even-numbered lines are always blank)

sed ‘n;d’

# insert a blank line above every line which matches “regex”

sed ‘/regex/{x;p;x;}’

# insert a blank line below every line which matches “regex”

sed ‘/regex/G’

# insert a blank line above and below every line which matches “regex”

sed ‘/regex/{x;p;x;G;}’

NUMBERING:

# number each line of a file (simple left alignment). Using a tab (see # note on ‘\t’ at end of file) instead of space will preserve margins.

sed = filename | sed ‘N;s/\n/\t/’

# number each line of a file (number on left, right-aligned)

sed = filename | sed ‘N; s/^/ /; s/ *\(.\{6,\}\)\n/\1 /’

# number each line of file, but only print numbers if line is not blank

sed ‘/./=’ filename | sed ‘/./N; s/\n/ /’ # count lines (emulates “wc -l”) sed -n ‘$=’

TEXT CONVERSION AND SUBSTITUTION:

# IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format. sed ‘s/.$//’

# assumes that all lines end with CR/LF

sed ‘s/^M$//’

# in bash/tcsh, press Ctrl-V then Ctrl-M

sed ‘s/\x0D$//’

# works on ssed, gsed 3.02.80 or higher

# IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format.

sed “s/$/`echo -e \\\r`/”

# command line under ksh

sed ‘s/$’”/`echo \\\r`/”

# command line under bash

sed “s/$/`echo \\\r`/”

# command line under zsh

sed ‘s/$/\r/’

# gsed 3.02.80 or higher

# IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format.

sed “s/$//”

# method 1

sed -n p

# method 2

# IN DOS ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.

# Can only be done with UnxUtils sed, version 4.0.7 or higher. The

# UnxUtils version can be identified by the custom “ — text” switch

# which appears when you use the “ — help” switch. Otherwise, changing

# DOS newlines to Unix newlines cannot be done with sed in a DOS

# environment. Use “tr” instead. sed “s/\r//” infile >outfile