Modifiers

Modifiers edit a history entry, allowing it to be repurposed. Some modifiers simply remove part of the entry. For instance, h removes everything that comes after the modifier, so specifying -h home/jwl would remove /music/pogues from the entry /home/jwl/music/pogues. Conversely, using /music/pogues would delete /home/jwl/ from the same entry. Similarly, using r with .odt would omit the extension from a LibreOffice file, while e would leave only .odt. With p, though, the event would only display without being executed, which could be handy if you are unsure exactly which history entry you want or decide to check the syntax before running it. Still other modifiers use a sed-like replacement that can save typing. For example, if you were backing up a file called draft1.odt but typed darft for the name of both the source and target file, you could correct both misspellings at the same time with

!!:gs/draft/darft

to run the command correctly. Should you require the same correction again, !!:g& will reapply it.

Alternate Histories

If all these possibilities are not enough, there are at least two alternatives. Instead of using the history command's options, you could pipe through grep, using the structure

history | grep TEXT

which, if you are already familiar with grep, could save you the need to learn the intricacies of another command and avoid the need to guess the location of the correct entry, although you would have to copy and paste to run it (Figure 4).

Figure 4: Piping history through grep can be an efficient way to search the history entries.

A more comprehensive alternative might be McFly [2], a replacement named for the main character in the Back to the Future movies (Figure 5). Using an SQLite database, McFly takes context into consideration in its output, doing the HISTTIMEFORMAT variable several times better. Among other things, McFly's suggestions are influenced by how often you run a command, when you last ran the command, and whether you've previously selected the command from McFly. In addition, McFly lets you run the command in the same directory as before, consider the commands you've previously run before the command you are searching for, and tell whether the command failed last time, which probably means you would not want to run it again. However, McFly is not yet a complete replacement for history.

Figure 5: McFly is a history alternative that uses AI to select results.

Conclusion

The history command offers plenty of ways to enhance your work at the command line. The fact that a direct substitution has not arrived before now is a tribute to the efficiency and versatility of the history command.