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updated man page

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Yann Collet 2016-10-31 18:10:32 -07:00
parent fe92398918
commit 3d197d4c8c
2 changed files with 67 additions and 10 deletions
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README.md
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@ -20,7 +20,7 @@ As a reference, several fast compression algorithms were tested and compared on
| Name | Ratio | C.speed | D.speed |
|-------------------------|-------|--------:|--------:|
| | | MB/s | MB/s |
|**zstd 0.8.2 -1** |**2.877**| **330** | **940** |
| **zstd 0.8.2 -1** |**2.877**| **330** | **940** |
| [zlib] 1.2.8 deflate -1 | 2.730 | 95 | 360 |
| brotli 0.4 -0 | 2.708 | 320 | 375 |
| QuickLZ 1.5 | 2.237 | 510 | 605 |

75
programs/zstd.1
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@ -27,16 +27,70 @@ is equivalent to
.SH DESCRIPTION
.PP
\fBzstd\fR is a fast lossless compression algorithm.
\fBzstd\fR is a fast lossless compression algorithm
and data compression tool,
with command line syntax similar to \fB gzip (1) \fR and \fB xz (1) \fR .
It is based on the \fBLZ77\fR family, with further FSE & huff0 entropy stages.
\fBzstd\fR offers configurable compression speed, with fast modes at > 200 MB/s per core.
It also features a very fast decoder, with speed > 500 MB/s per core.
\fBzstd\fR offers highly configurable compression speed,
with fast modes at > 200 MB/s per core,
and strong modes nearing lzma compression ratios.
It also features a very fast decoder, with speeds > 500 MB/s per core.
\fBzstd\fR command line is generally similar to gzip, but features the following differences :
- Source files are preserved by default
It's possible to remove them automatically by using \fB--rm\fR command
\fBzstd\fR command line syntax is generally similar to gzip,
but features the following differences :
- Source files are preserved by default.
It's possible to remove them automatically by using \fB--rm\fR command.
- When compressing a single file, \fBzstd\fR displays progress notifications and result summary by default.
Use \fB-q\fR to turn them off
Use \fB-q\fR to turn them off
.PP
.B zstd
compresses or decompresses each
.I file
according to the selected operation mode.
If no
.I files
are given or
.I file
is
.BR \- ,
.B zstd
reads from standard input and writes the processed data
to standard output.
.B zstd
will refuse (display an error and skip the
.IR file )
to write compressed data to standard output if it is a terminal.
Similarly,
.B zstd
will refuse to read compressed data
from standard input if it is a terminal.
.PP
Unless
.B \-\-stdout
is specified,
.I files
are written to a new file whose name is derived from the source
.I file
name:
.IP \(bu 3
When compressing, the suffix
.B .zst
is appended to the source filename to get the target filename.
.IP \(bu 3
When decompressing, the
.B .zst
suffix is removed from the filename to get the target filename.
.SS "Concatenation with .zst files"
It is possible to concatenate
.B .zst
files as is.
.B zstd
will decompress such files as if they were a single
.B .zst
file.
@ -112,7 +166,8 @@ No files are created or removed.
.TP
.BR \--no-dictID
do not store dictionary ID within frame header (dictionary compression).
the decoder will have to rely on implicit knowledge about which dictionary to use, it won't be able to check if it's correct.
The decoder will have to rely on implicit knowledge about which dictionary to use,
it won't be able to check if it's correct.
.TP
.B \-o file
save result into `file` (only possible with a single INPUT-FILE)
@ -125,6 +180,8 @@ No files are created or removed.
.TP
.BR \--[no-]sparse
enable / disable sparse FS support, to make files with many zeroes smaller on disk.
Creating sparse files may save disk space and speed up the decompression
by reducing the amount of disk I/O.
default : enabled when output is into a file, and disabled when output is stdout.
This setting overrides default and can force sparse mode over stdout.
.TP
@ -162,7 +219,7 @@ No files are created or removed.
All arguments after -- are treated as files
.SH DICTIONARY
.SH DICTIONARY BUILDER
.PP
\fBzstd\fR offers \fIdictionary\fR compression, useful for very small files and messages.
It's possible to train \fBzstd\fR with some samples, the result of which is saved into a file called `dictionary`.