X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=vbig.1;h=feb4192619569ca3cf63d2c3a89b2af8df492100;hb=56ba86fffaccf9ae9d8aabb182f1ff918484a210;hp=ccd98f247ba5efc724b8785ef91987384a3d5651;hpb=9b65d43d40c9f3c85634b22c6626199736cd5afb;p=vbig.git diff --git a/vbig.1 b/vbig.1 index ccd98f2..feb4192 100644 --- a/vbig.1 +++ b/vbig.1 @@ -1,6 +1,7 @@ \" \" This file is part of vbig. \" Copyright (C) 2011 Richard Kettlewell +\" Copyright (C) 2013 Ian Jackson \" \" This program is free software: you can redistribute it and/or modify \" it under the terms of the GNU General Public License as published by @@ -19,25 +20,61 @@ .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 SIZE +\fBvbig \fR[\fB--seed \fRSEED\fR] [\fB--both\fR|\fB--create\fR|\fB--verify\fR] \fIPATH \fR[\fISIZE\fR] .br -\fBvbig --help +\fBvbig \-\-help .br -\fBvbig --version +\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 +By default vbig will generate a new random seed, write data to the +specified file or device until the device is full, read the data back +to check that everything written was properly stored, and report +the device's size. Ideally, if you have privilege to do so, you +would also specify \fB-f\fR (to flush the operating system disk +cache between the write and read). Also you probably want \fB-p\fR. +.PP +\fBPATH\fR can refer to an ordinary file on a mounted file system, +which vbig will create or truncate as necessary, or a block device. +Note that if its a file vbig won't delete it after it's done. Also, +be careful when specifying a block device - don't accidentally +overwrite a filesystem you care about! vbig doesn't do sanity checks +and is as dangerous as \fBdd\fR. +.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. 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. @@ -51,10 +88,19 @@ by the equivalent \fB--create\fR call. Flush cached data after creating the file or before verifying it. On some platforms, only root can use this option. .TP +.B --progress\fR, \fB-p +Show the progress (in bytes) on stdout. +.TP +.B --entire\fR, \fB-e +When writing, keep going until the device is full (No space left +on device). When reading, keep going until the end of the file +or device. \fISIZE\fR should not be specified. The actual size +written or verified will be printed to stdout. +.TP .B --help\fR, \fB-h Displays a usage message. .TP -.B --version\fR, \fB-h +.B --version\fR, \fB-V Displays the version strings. .SH AUTHOR Richard Kettlewell