X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=vms%2Fgzip.hlp;fp=vms%2Fgzip.hlp;h=0000000000000000000000000000000000000000;hb=dc84183747ce1703eb99685b5dbde1f65a143c06;hp=0bee53673a0326739536310ee5853da77752285f;hpb=a2016c1de6e4884f6c8ed5cc498f3bf821c25ca4;p=debian%2Fgzip diff --git a/vms/gzip.hlp b/vms/gzip.hlp deleted file mode 100644 index 0bee536..0000000 --- a/vms/gzip.hlp +++ /dev/null @@ -1,297 +0,0 @@ -1 GZIP -NAME - gzip, gunzip, zcat - compress or expand files - -SYNOPSIS - gzip [ -acdfhlLnNrtvV19 ] [-S suffix] [ name ... ] - gunzip [ -acfhlLnNrtvV ] [-S suffix] [ name ... ] - zcat [ -fhLV ] [ name ... ] - -2 DESCRIPTION - Gzip reduces the size of the named files using Lempel-Ziv - coding (LZ77). Whenever possible, each file is replaced by - one with the extension .gz, while keeping the same ownership - modes, access and modification times. (The default exten- - sion is -gz for VMS, z for MSDOS, OS/2 FAT, Windows NT FAT - and Atari.) If no files are specified, or if a file name is - "-", the standard input is compressed to the standard out- - put. Gzip will only attempt to compress regular files. - - If the compressed file name is too long for its file system, - gzip truncates it. Gzip attempts to truncate only the parts - of the file name longer than 3 characters. (A part is del- - imited by dots.) If the name consists of small parts only, - the longest parts are truncated. For example, if file names - are limited to 14 characters, gzip.msdos.exe is compressed - to gzi.msd.exe.gz. Names are not truncated on systems which - do not have a limit on file name length. - - By default, gzip keeps the original file name and timestamp - in the compressed file. These are used when decompressing - the file with the -N option. This is useful when the - compressed file name was truncated or when the time stamp - was not preserved after a file transfer. - - Compressed files can be restored to their original form - using gzip -d or gunzip or zcat. If the original name saved - in the compressed file is not suitable for its file system, - a new name is constructed from the original one to make it - legal. - - gunzip takes a list of files on its command line and - replaces each file whose name ends with .gz, -gz, .z, -z, _z - or .Z and which begins with the correct magic number with an - uncompressed file without the original extension. gunzip - also recognizes the special extensions .tgz and .taz as - shorthands for .tar.gz and .tar.Z respectively. When - compressing, gzip uses the .tgz extension if necessary - instead of truncating a file with a .tar extension. - - gunzip can currently decompress files created by gzip, zip, - compress, compress -H or pack. The detection of the input - format is automatic. When using the first two formats, - gunzip checks a 32 bit CRC. For pack, gunzip checks the - uncompressed length. The standard compress format was not - designed to allow consistency checks. However gunzip is - sometimes able to detect a bad .Z file. If you get an error - when uncompressing a .Z file, do not assume that the .Z file - is correct simply because the standard uncompress does not - complain. This generally means that the standard uncompress - does not check its input, and happily generates garbage out- - put. The SCO compress -H format (lzh compression method) - does not include a CRC but also allows some consistency - checks. - - Files created by zip can be uncompressed by gzip only if - they have a single member compressed with the 'deflation' - method. This feature is only intended to help conversion of - tar.zip files to the tar.gz format. To extract zip files - with several members, use unzip instead of gunzip. - - zcat is identical to gunzip -c. (On some systems, zcat may - be installed as gzcat to preserve the original link to - compress.) zcat uncompresses either a list of files on the - command line or its standard input and writes the - uncompressed data on standard output. zcat will uncompress - files that have the correct magic number whether they have a - .gz suffix or not. - - Gzip uses the Lempel-Ziv algorithm used in zip and PKZIP. - The amount of compression obtained depends on the size of - the input and the distribution of common substrings. Typi- - cally, text such as source code or English is reduced by - 60-70%. Compression is generally much better than that - achieved by LZW (as used in compress), Huffman coding (as - used in pack), or adaptive Huffman coding (compact). - - Compression is always performed, even if the compressed file - is slightly larger than the original. The worst case expan- - sion is a few bytes for the gzip file header, plus 5 bytes - every 32K block, or an expansion ratio of 0.015% for large - files. Note that the actual number of used disk blocks - almost never increases. gzip preserves the mode, ownership - and timestamps of files when compressing or decompressing. - -2 OPTIONS - -a --ascii - Ascii text mode: convert end-of-lines using local con- - ventions. This option is supported only on some non- - Unix systems. For MSDOS, CR LF is converted to LF when - compressing, and LF is converted to CR LF when - decompressing. - - -c --stdout --to-stdout - Write output on standard output; keep original files - unchanged. If there are several input files, the out- - put consists of a sequence of independently compressed - members. To obtain better compression, concatenate all - input files before compressing them. - - -d --decompress --uncompress - Decompress. - - -f --force - Force compression or decompression even if the file has - multiple links or the corresponding file already - exists, or if the compressed data is read from or writ- - ten to a terminal. If the input data is not in a format - recognized by gzip, and if the option --stdout is also - given, copy the input data without change to the stan- - dard output: let zcat behave as cat. If -f is not given, - and when not running in the background, gzip prompts to - verify whether an existing file should be overwritten. - - -h --help - Display a help screen and quit. - - -l --list - For each compressed file, list the following fields: - - compressed size: size of the compressed file - uncompressed size: size of the uncompressed file - ratio: compression ratio (0.0% if unknown) - uncompressed_name: name of the uncompressed file - - The uncompressed size is given as -1 on VMS because it - it is not possible to seek reliably to the end of the - compressed file, where this size is stored. - - In combination with the --verbose option, the following - fields are also displayed: - - method: compression method - crc: the 32-bit CRC of the uncompressed data - date & time: time stamp for the uncompressed file - - The compression methods currently supported are - deflate, compress, lzh (SCO compress -H) and pack. The - crc is given as ffffffff on VMS for the reason given - above about the uncompressed size. - - With --name, the uncompressed name, date and time are - those stored within the compress file if present. - - With --verbose, the size totals and compression ratio - for all files is also displayed, unless some sizes are - unknown. With --quiet, the title and totals lines are - not displayed. - - -L --license - Display the gzip license and quit. - - -n --no-name - When compressing, do not save the original file name - and time stamp by default. (The original name is always - saved if the name had to be truncated.) When - decompressing, do not restore the original file name if - present (remove only the gzip suffix from the - compressed file name) and do not restore the original - time stamp if present (copy it from the compressed - file). This option is the default when decompressing. - - -N --name - When compressing, always save the original file name - and time stamp; this is the default. When decompress- - ing, restore the original file name and time stamp if - present. This option is useful on systems which have a - limit on file name length or when the time stamp has - been lost after a file transfer. - - -q --quiet - Suppress all warnings. - - -r --recursive - Travel the directory structure recursively. If any of - the file names specified on the command line are direc- - tories, gzip will descend into the directory and - compress all the files it finds there (or decompress - them in the case of gunzip ). - - -S suf --suffix suf - Use suffix suf instead of -gz. Any suffix can be - given, but suffixes other than -z and -gz should be - avoided to avoid confusion when files are transferred - to other. A null suffix forces gunzip to try - decompression on all given files regardless of suffix, - as in: - - gunzip --suffix "" *.* - - Previous versions of gzip used the -z suffix. This was - changed to avoid a conflict with pack on Unix. - - -t --test - Test. Check the compressed file integrity. - - -v --verbose - Verbose. Display the name and percentage reduction for - each file compressed or decompressed. - - -V --version - Version. Display the version number and compilation - options then quit. - - -# --fast --best - Regulate the speed of compression using the specified - digit #, where -1 or --fast indicates the fastest - compression method (less compression) and -9 or --best - indicates the slowest compression method (best compres- - sion). The default compression level is -6 (that is, - biased towards high compression at expense of speed). - -2 ENVIRONMENT - The environment variable GZIP_OPT can hold a set of default - options for gzip. These options are interpreted first and - can be overwritten by explicit command line parameters. For - example: - define GZIP_OPT "-8 -v" - -2 SEE ALSO - compress, zip, unzip - -2 DIAGNOSTICS - Exit status is normally 0; if an error occurs, exit status - is 1. If a warning occurs, exit status is 2. - - Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...] - Invalid options were specified on the command line. - file: not in gzip format - The file specified to gunzip has not been - compressed. - file: Corrupt input. Use zcat to recover some data. - The compressed file has been damaged. The data up to - the point of failure can be recovered using - define /user sys$output file.recover - zcat file - file: compressed with xx bits, can only handle yy bits - File was compressed (using LZW) by a program that - could deal with more bits than the decompress code - on this machine. Recompress the file with gzip, - which compresses better and uses less memory. - file: already has -gz suffix -- no change - The file is assumed to be already compressed. - Rename the file and try again. - file already exists; do you wish to overwrite (y or n)? - Respond "y" if you want the output file to be - replaced; "n" if not. - gunzip: corrupt input - A SIGSEGV violation was detected which usually means - that the input file has been corrupted. - xx.x% - Percentage of the input saved by compression. - (Relevant only for -v and -l.) - -- not a regular file or directory: ignored - When the input file is not a regular file or direc- - tory, it is left unaltered. - -2 CAVEATS - On VMS: - - upper case options need quotes: gzip "-V". - - restoration of timestamps and version numbers is not supported - - If a compressed file already exists, gzip -f overwrites it, it - does not create a new version. - - multi-part gzip files are not supported. - - gunzip does not preserve the input file format. You can use a - separate utility to restore the original format. - - gunzip and zcat can be used only if you have created the - links to gzip as documented in makegzip.com. Otherwise - you must use explicit parameters ("gzip -c" or "gzip -dc"). - - gzip --list cannot give the uncompressed size and crc. - - When writing compressed data to a tape, it is generally - necessary to pad the output with zeroes up to a block boun- - dary. When the data is read and the whole block is passed to - gunzip for decompression, gunzip detects that there is extra - trailing garbage after the compressed data and emits a warn- - ing by default. You have to use the --quiet option to - suppress the warning. This option can be set in the GZIP_OPT - environment variable as in: - define GZIP_OPT "-q" - -2 BUGS - On VMS, files in VFC record format are not correctly handled by - the C runtime library (the linefeed character is suppressed). - - In some rare cases, the --best option gives worse compres- - sion than the default compression level (-6). On some highly - redundant files, compress compresses better than gzip.