Sgrep

If you're looking for a speedy way to search large files, then Sgrep (sorted grep) is a utility that's worth considering. This open-source command-line tool searches for lines within sorted input files that match a key term, and then outputs the matching lines. While Sgrep may be faster than the traditional Unix grep software, it does come with several restrictions which may limit its usefulness for some users.

Sgrep requires all input files to be sorted and in regular file format. Additionally, the sort key must be located at the beginning of each line, and the search key will only match phrases that appear at the start of lines. Unfortunately, if you're looking for support for regular expressions, you may be disappointed, as this feature is not available in Sgrep.

Despite these restrictions, Sgrep uses a binary search algorithm that is incredibly quick, eliminating half of the remaining input with each iteration. In fact, the additional iteration that's required when doubling the input file size is negligible. Overall, Sgrep can be a powerful tool that lets you search large sorted files quickly, and its open-source status means that it's available to all users for free.