The pitch: cuniq is a dedicated command line tool for counting unique lines in text input. If you find yourself
frequently running commands like sort -u | wc -l or sort | uniq -c you will find improved performance by using cuniq
instead.
The anti-pitch: For small inputs you're fine using sort and uniq, as we're talking millisecond-savings by switching
to cuniq. However, if you've been using sort | uniq | wc -l you should switch to sort -u | wc -l, as it's free
performance gain without having to go outside GNU coreutils.
- Multithreading support
- Show a report of the number of times each distinct line appears with
--report --mode=near-exactgains extra performance by ignoring hash collisions. With 64-bit hashing the odds of a collision are low. Unless you have in excess of 10 million distinct lines you don't need to worry about it.--mode=estimategains even more performance by using a probabilistic estimate instead of an exact count. Useful if you can tolerate a small (~1%) margin of error.
As of this writing and to the best of my knowledge, cuniq has the best performance across all tools in its class.
cuniq has been benchmarked against various combinations of GNU coreutils (sort, uniq, and wc) as well as other
hashing-based Rust utilities runiq, sortuniq,
and huniq.
You should not use runiq 2.0.0 or sortuniq 0.3.0 for counting unique lines: they underperform cuniq
in all cases, and in many cases their performance is on par with or even worse than sort -u | wc -l.
For counting cuniq reliably outperforms GNU sort in all cases.
For reporting line occurrence counts cuniq reliably outperforms GNU uniq in all cases except one:
Note
If your input has extremely few duplicates and you want a sorted report, than you're better off using sort | uniq -c.
This is because with extremely few duplicates both approaches must sort nearly all of the input, but cuniq also spends
time building a hash table.
More data and technical details on the benchmarking and profile-guided optimization that went into creating cuniq are available in PERFORMANCE.md.
cuniq has compatible output with corresponding GNU coreutils commands:
| GNU coreutils command | cuniq equivalent | Effect | Notes |
|---|---|---|---|
sort | uniq | wc -l |
cuniq |
Count of unique lines | |
sort -u | wc -l |
cuniq |
Count of unique lines | this GNU coreutils command is more performant than the above |
sort | uniq -c |
cuniq -c |
Unsorted report of unique line counts | output order differs between the two commands |
sort | uniq -c |
cuniq -cs |
Sorted report of unique line counts |
Firstly, Install Rust.
Install from crates.io:
RUSTFLAGS="-C target-cpu=native" cargo install cuniq
Alternatively, install from GitHub:
RUSTFLAGS="-C target-cpu=native" cargo install --git=https://github.com/zkxs/cuniq
Download cuniq from the latest release, and save it to a location of your choice
yay -S cuniq
cuniq can accept lines from stdin or from a list of files.
Usage: cuniq [OPTIONS] [FILES]...
Arguments:
[FILES]...
Files to process
Options:
-c, --report
Instead of printing total unique lines, print a report showing occurrence count of each line. This is only
compatible with "exact" mode (the default)
-s, --sort
Sort report output alphabetically by line. Has no effect unless used with `--report`
-m, --mode <MODE>
Sets the algorithm used to count (or estimate) cardinality
Possible values:
- exact: Uses a hash table to exactly count cardinality. The size of the hash table is proportional to
the cardinality of the input. You may use the `--size` flag to set the initial capacity of the internal hash
table. For very large inputs `--size` may help reduce expensive hash table reallocations. Avoid setting
`--size` for small datasets
- near-exact: Uses a hash table to exactly count cardinality, but does not store the original line. This mode
is faster than "exact" mode, but hash collision will result in under-counting the cardinality by one.
However, hash collisions for a 64-bit hash are exceedingly unlikely. The size of the hash table is
proportional to the cardinality of the input. You may use the `--size` flag to set the initial capacity of
the internal hash table. For very large inputs `--size` may help reduce expensive hash table reallocations.
Avoid setting `--size` for small datasets. This mode is not compatible with `--report`
- estimate: Uses the HyperLogLog algorithm to estimate cardinality with fixed memory. Use the `--size` flag
to specify the number of 1-byte registers to use. More registers will increase estimate accuracy. By
default, 65536 is used. This mode is not compatible with `--report`
[default: exact]
-n, --size <SIZE>
Set the size used by the selected counting mode. See the `--mode` documentation for how this affects each
counting mode
--threads <THREADS>
Set the number of threads used to perform the count. By default, the number of logical cores is used
--no-stdin
Disable checking stdin for input. May yield a small performance improvement when only reading input from files
--memmap
Force reading files via memmap. This may yield improved performance for large files. If the binary was built
without memmap support, using this flag will result in an error
--no-memmap
Disable reading files via memmap, instead falling back to normal reads. By default, cuniq will try to use
memmap if it thinks it will be faster. Disabling memmap may yield improved performance for small files
-h, --help
Print help (see a summary with '-h')
-V, --version
Print version
cuniq is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
cuniq is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
A full list of dependencies is available in Cargo.toml, or a breakdown of dependencies by license can be
generated with cargo deny list.