How to set sort(1) to use a custom collation?

Question

I have a text file containing one record per line which I'd like to sort alphabetically, except that I want '-' to sort after '[' and ']'. (The natural sort order has '-' before the square brackets.) Is there a way to modify the collation that sort(1) uses in order to achieve this?

Answer 1

One way would be to substitute a character that doesn't appear in your data, but sorts after the brackets (in some locale).

sed 's/-/|/g' inputfile | LC_ALL=C sort | sed 's/|/-/g' > outputfile

This is obviously not an ideal solution.

Answer 2

You could do it with perl:

perl -e 'print sort { (($a =~ /^-/ && $b =~ /^[\[\]]/) || ($a =~ /^[\[\]]/ && $b =~ /^-/)) ? ($b cmp $a) : ($a cmp $b) } (<>)' <filename>

Answer 3

You will probably want to apply one of the suggested workarounds, but the answer to your question is no(t easily). If you want to change how sort sorts, and none of the special sort orders offered by the command-line options suit you, you will need to define your own locale. See localedef.