.SH NAME
vbig \- create or verify a large but pseudo-random file
.SH SYNOPSIS
-\fBvbig \fR[\fB--seed \fRSEED\fR] \fB--create\fR|\fB--verify \fIPATH \fR[\fISIZE\fR]
+\fBvbig \fR[\fB--seed \fRSEED\fR] [\fB--both\fR|\fB--create\fR|\fB--verify\fR] \fIPATH \fR[\fISIZE\fR]
.br
\fBvbig --help
.br
\fBvbig --version
.SH DESCRIPTION
-\fBvbig\fR either creates a file of specified size full of predictable
-psuedo-random data, or verifies that it has the expected contents.
+\fBvbig\fR creates a file of specified size full of predictable
+psuedo-random data, and/or verifies that it has the expected contents.
The intended use is to test whether storage media really do what they
say on the tin.
.PP
\fISIZE\fR may end with \fBK\fR, \fBM\fR or \fBG\fR to select (binary)
kilobytes, megabytes or gigabytes.
The size is mandatory when creating a file but optional when verifying
-it, unless \-\-entire is specified.
+it, unless \-\-entire is specified. If \fBSIZE\fR not specified when
+writing-then-verifying, it is as if \fB\-\-entire\fR was specified.
+.PP
+If no seed or seed file is specified:
+in \fB--both\fR mode a fresh random seed is read from the system's
+random number generator; in other modes a fixed default seed is used.
.SH OPTIONS
.TP
.B --seed\fR, \fB-s \fISEED
Specifies the random seed to use.
Optional.
.TP
+.B --seed-file\fR, \fB-S \fISEED-FILE
+Specifies wehre the random seed should be read from. The
+first \fISEED-LENGTH\fR bytes will be used, or the whole file
+if it is shorter.
+.TP
+.B --seed-length\fR, \fB-L \fISEED-LENGTH
+Specifies the (maximum) seed length in bytes.
+Optional; default is 2048.
+.TP
+.B --both\fR, \fB-b
+Selects both mode.
+\fIPATH\fR will be filled with \fISIZE\fR psuedo-random bytes and
+then read to check that it contains the data just written.
+This is the default.
+.TP
.B --create\fR, \fB-c
Selects create mode.
\fIPATH\fR will be filled with \fISIZE\fR psuedo-random bytes.
~ianmdlvl / vbig.git / blobdiff