# 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;}' 

 # 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 '$=' 

 # 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         # UnxUtils sed v4.0.7 or higher tr -d r <infile >outfile            # GNU tr version 1.22 or higher  # delete leading whitespace (spaces, tabs) from front of each line # aligns all text flush left sed 's/^[ t]*//'                    # see note on 't' at end of file  # delete trailing whitespace (spaces, tabs) from end of each line sed 's/[ t]*$//'                    # see note on 't' at end of file  # delete BOTH leading and trailing whitespace from each line sed 's/^[ t]*//;s/[ t]*$//'  # insert 5 blank spaces at beginning of each line (make page offset) sed 's/^/     /'  # align all text flush right on a 79-column width sed -e :a -e 's/^.{1,78}$/ &/;ta'  # set at 78 plus 1 space  # center all text in the middle of 79-column width. In method 1, # spaces at the beginning of the line are significant, and trailing # spaces are appended at the end of the line. In method 2, spaces at # the beginning of the line are discarded in centering the line, and # no trailing spaces appear at the end of lines. sed  -e :a -e 's/^.{1,77}$/ & /;ta'                     # method 1 sed  -e :a -e 's/^.{1,77}$/ &/;ta' -e 's/( *)1/1/'  # method 2  # substitute (find and replace) "foo" with "bar" on each line sed 's/foo/bar/'             # replaces only 1st instance in a line sed 's/foo/bar/4'            # replaces only 4th instance in a line sed 's/foo/bar/g'            # replaces ALL instances in a line sed 's/(.*)foo(.*foo)/1bar2/' # replace the next-to-last case sed 's/(.*)foo/1bar/'            # replace only the last case  # substitute "foo" with "bar" ONLY for lines which contain "baz" sed '/baz/s/foo/bar/g'  # substitute "foo" with "bar" EXCEPT for lines which contain "baz" sed '/baz/!s/foo/bar/g'  # change "scarlet" or "ruby" or "puce" to "red" sed 's/scarlet/red/g;s/ruby/red/g;s/puce/red/g'   # most seds gsed 's/scarlet|ruby|puce/red/g'                # GNU sed only  # reverse order of lines (emulates "tac") # bug/feature in HHsed v1.5 causes blank lines to be deleted sed '1!G;h;$!d'               # method 1 sed -n '1!G;h;$p'             # method 2  # reverse each character on the line (emulates "rev") sed '/n/!G;s/(.)(.*n)/&21/;//D;s/.//'  # join pairs of lines side-by-side (like "paste") sed '$!N;s/n/ /'  # if a line ends with a backslash, append the next line to it sed -e :a -e '/$/N; s/n//; ta'  # if a line begins with an equal sign, append it to the previous line # and replace the "=" with a single space sed -e :a -e '$!N;s/n=/ /;ta' -e 'P;D'  # add commas to numeric strings, changing "1234567" to "1,234,567" gsed ':a;s/B[0-9]{3}>/,&/;ta'                     # GNU sed sed -e :a -e 's/(.*[0-9])([0-9]{3})/1,2/;ta'  # other seds  # add commas to numbers with decimal points and minus signs (GNU sed) gsed -r ':a;s/(^|[^0-9.])([0-9]+)([0-9]{3})/12,3/g;ta'  # add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.) gsed '0~5G'                  # GNU sed only sed 'n;n;n;n;G;'             # other seds