.\" Copyright (c) 2001-2003 Allan Saddi <allan@saddi.com>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY ALLAN SADDI AND HIS CONTRIBUTORS ``AS IS''
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL ALLAN SADDI OR HIS CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $Id: sha.1 351 2003-02-23 23:24:40Z asaddi $
.TH SHA 1 "August 19, 2001"
.SH NAME
sha - file hashing utility
.SH SYNOPSIS
.TP 4
.B sha
.RB [ -12345Vh ]
.RI [ file
.IR ... ]
.SH DESCRIPTION
.B sha
is a simple program that hashes files. It uses the National
Institute of Standards and Technology's Secure Hash Algorithm.
It can use SHA-1, SHA-256, SHA-384, or SHA-512, which generate
respectively, hashes of 160, 256, 384, or 512 bits.
.B sha
can be used in scripts to do, for example, file integrity checking.
.SH OPTIONS
.TP
.B -1
Use SHA-1, which produces a 160-bit hash (40 hex digits).
.TP
.B -2
Use SHA-256, which produces a 256-bit hash (64 hex digits).
.TP
.B -3
Use SHA-384, which produces a 384-bit hash (96 hex digits).
.TP
.B -5
Use SHA-512, which produces a 512-bit hash (128 hex digits).
.TP
.B -V
Display version information.
.TP
.B -h
Display help summary.
.TP
.I file ...
One or more files to hash. If no files are given, stdin is hashed.
.P
If neither
.BR -1 ", " -2 ", " -3 ", or " -5
are given, then SHA-1 is used. (But see note about SHA_DEFAULT below.)
.SH ENVIRONMENT
.TP
SHA_DEFAULT
The default hash algorithm to use. ``1'' denotes SHA-1, ``2'' denotes
SHA-256, ``3'' denotes SHA-384, and ``5'' denotes SHA-512. Only the first
character is significant. If not defined, SHA-1 is the default.