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A live-updating version of the UNIX wc command.
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.circleci Lock down dep version Apr 28, 2018


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A live-updating version of the UNIX wc command.


You can get a prebuilt binary for every major platform from the Releases page. Just extract it somewhere under your PATH and you're good to go.

Alternatively, use go get to build from source:

go get -u

On Debian-compatible Linux distributions such as Ubuntu, you can also use the experimental APT repository:

echo 'deb [allow-insecure=yes] any main' |
  sudo tee /etc/apt/sources.list.d/lwc.list
sudo apt update
sudo apt install lwc


lwc [OPTION]... [FILE]...
lwc [OPTION]... --files0-from=F

Without any options, lwc will count the number of lines, words, and bytes in standard input, and write them to standard output. Contrary to wc, it will also update standard output while it is still counting.

All the standard wc options are supported:

  • --lines or -l
  • --words or -w
  • --chars or -m
  • --bytes or -c
  • --max-line-length or -L
  • --files0-from=F
  • --help
  • --version

In addition, the output update interval can be configured by passing either --interval=TIME or -i TIME, where TIME is a duration in milliseconds. The default update interval is 100 ms.


Count the number of lines in a big file:

lwc --lines big-file

Run a slow command and count the number of lines and words logged:

slow-command | lwc --lines --words

Benchmark lwc's throughput by counting random bytes (press Ctrl+C to exit):

lwc --bytes < /dev/urandom


You can mostly use lwc as a drop-in replacement for wc. However, you should be aware of the following:

  • The behavior of the --words and --chars options is slightly different from wc's implementation. You might get different values with certain binary data.

  • While lwc is pretty fast, you won't get the same raw throughput as with wc. The reason for that is (probably) twofold: the code isn't optimized for performance, and a Go implementation is no match for a C one.

JavaScript Version

This utility briefly existed as a Node.js package. I'm keeping the code around for educational purposes, but I will no longer be maintaining it.


Tim De Pauw



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