The file looks like this (one big line):
a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a; etc...... Now I want to cut the text and do a line break after every fifth semicolon (;) so it looks like this:
a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; etc.... How do I do this?
With tr and paste
tr ';' '\n' < semicolons | paste -d';' - - - - - Tests
$ cat semicolons a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a $ tr ';' '\n' < semicolons | paste -d';' - - - - - a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a a;a;a;a;a Both tr and paste are specified in POSIX standard.
To add the required semicolon ; at the end of the lines
tr ';' '\n' < semicolons | paste -d';' - - - - - | sed s/$/\;/ Tests
$ tr ';' '\n' < semicolons | paste -d';' - - - - - | sed s/$/\;/ a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; 
tr ';' '\n' < semicolons | paste -sd';;;;\n' Purely using GNU sed substitution:
sed 's/\(\([^;]*;\)\{5\}\)/\1\n/g' or without all the escaping backslashes using -E (thanks @JoL):
sed -E 's/(([^;]*;){5})/\1\n/g' Example:
$ cat test.txt a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a;a; etc...... $ cat test.txt | sed 's/\(\([^;]*;\)\{5\}\)/\1\n/g' a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a;a; a;a;a;a; etc...... Explanation:
\([^;]*;\): regex capture group matching all characters up to and including a semi-colon.\(\([^;]*;\)\{5\}\): regex capture group matching five occurrences of the above. In the sed command, this will be matched into \1.s/\(\([^;]*;\)\{5\}\)/\1\n/g: substitute (s/) every occurrence (/g) of the group of five occurrences of all characters up to and including a semicolon (\(\([^;]*;\)\{5\}\)) with itself (\1), but followed by a newline character (\n).
-r (GNU option) or -E (GNU and POSIX option). I.e. sed -E 's/(([^;]*;){5})/\1\n/g' Sed editor method we place a newline after the 5th semicolon, print upto the newline, remove upto newline, rinse n repeat till you run out of the pattern space.
$ sed -e 's/;/;\n/5;P;D' file With Perl, use semicolon as field separator and print in bunches of 5 with semicolons as OFS and an empty field at the end to get the trailing semicolon printed :
$ perl -F\; -lane '$,=";"; print splice(@F, 0, 5), q() while @F; ' file Using Awk we look at a bunch of 5 fields and append a semicolon to the first 4 and semicolon + newline to the fifth. Then print the fields with a null separating them:
$ awk -F\; -vOFS= '{ for(i=1; i<=NF; i++) $(i) = $(i) (i%5 ? FS : FS RS) }1' file I find that while regexes are appropriate for this kind of task, I always do it with text editor macros for the visual help and simplicity.
Using vim, you can
set textwidth=20 or similarly low and
set wrap and if the file really needs editing, a simple macro like
qqf;f;f;f;f;i\n99999@q would do it.
