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The cat
command on Linux concatenates files together. It's often used to concatenate one file to nothing to print the single file's contents to the terminal. This is a quick way to preview the contents of a text file without having to open the file in a large application.
There's nothing wrong with cat
, but similar commands have been developed over the years, and the one with the most features is bat
.
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Developers call bat
, available under the terms of either the MIT License or the Apache License 2.0 (your choice), a "cat
clone with wings." There's probably a healthy debate over what those wings are, but for me, it's the syntax highlighting and line numbering. It's a highly visual feature and can be a great help when scanning through files.
Because you're likely to use the bat
output as the input for a second command, you can deactivate extra data like line numbers with the --plain
option. Supported terminals retain syntax highlighting.
The --plain
option is an alias for --style=plain
, which hints at just how many ways you can customize the command's output. Here are some of my favorite options for the --style
option:
That's not all of the style options, just the ones I use frequently.
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Did I say syntax highlighting was my favorite feature? I meant that Git integration is my favorite feature. The bat
command is Git-aware by default. When you're in a Git repository, you can use the --diff
option to view just the changes to a file since it was last committed.
For instance, imagine I'm in the Git repository of my zombie apocalypse game. I've recently updated some code, but I can't quite recall the extent of it.
$ bat --diff Zombie.java
1 public class Player {
2
3 private BufferedImage image;
4+ private Position pos;
5 private Health health;
6-
7 public Zombie() {
8 loadImage();
[...]
When a line has been added since the previous commit, a plus sign (+
) appears in the margin, and when a line has been changed or removed, a minus sign (-
) appears.
The --diff
option works only with Git. It's not a general-purpose diff tool.
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You can highlight a range of lines in a file. This isn't syntax highlighting, which bat
does automatically. Instead, this marks each line with a solid box, as if to mimic a highlighter you use on paper.
$ bat --highlight-line=20:26 ZombieCruncher.java
Your results may vary with this effect. On some screens, I have a feeling that instead of highlighting, this effect obfuscates due to a drop in contrast. Still, it's a visual marker that might be useful to some.
There are more features in bat
than what I've covered here, but these are the ones I use the most. The bat
command isn't strictly essential. Commands like cat
and more
, and even sed
or awk
in a pinch, perform basically the same function, but bat
consciously does it with a lot more style. And that counts for something, if you like the visual aid of colorful output and a little extra context.
To install bat on Fedora, use the package manager:
$ sudo dnf install bat
On other systems, you can download a binary release from the bat Git repository or build it using the crate
command.
Seth Kenlon is a UNIX geek and free software enthusiast. More about me