<ALGORITHM>sum - a Parallel Implementation of the <ALGORITHM> algorithm
# SYNOPSIS
<ALGORITHM>sum [_OPTIONS_] [_FILE_]...
# DESCRIPTION
Print or verify checksums by reading files in parallel, using the <ALGORITHM> algorithm.
When conditions are suitable, being able to hash multiple files in parallel can significantly increase performance with multi-file hashing operations. However, it can also significantly degrade performance depending on different factors with your particular system. Some factors to consider are:
- The type of storage being used,
- The type of processor(s) in the system,
- The latency of I/O operations,
- etc.
<ALGORITHM>sum is a standalone binary of the picca project that only runs the <ALGORITHM> algorithm. See **picca**(1) for information on the main binary.
# OPTIONS
With no FILE(s) specified, or when FILE is a dash (-), <ALGORITHM>sum will read from standard input.
**-c, ––check** _CHECK_
: Read checksums from the specified file and verify them. This argument can be specified multiple times to read checksums from multiple files.
**-d, ––debug**
: Enable debug output for troubleshooting purposes. Messages output to standard error.
**-f, ––canonicalize**
: Show canonicalized file paths; convert relative paths to absolute paths.
**-h, ––help**
: Show command usage and available options
**-t, ––threads** _THREADS_
: Use at most, at any given time, this number of threads. By default, <ALGORITHM>sum will detect the amount of processors on the system and use that as the thread count. Using 0 for this value results in the default behavior; this is the same as omitting this option.
**-V, ––version**
: Show the version of picca and exit
The following option is only useful when verifying checksums with the **-c** flag:
**-q, ––quiet**
: Only print checksums that fail verification; do not print anything to standard output if a verfication is successful. Helpful to limit the amount of information printed to the screen.
