1Dpkg::Compression(3perl) libdpkg-perl Dpkg::Compression(3perl)
2
6 Dpkg::Compression - simple database of available compression methods
7
9 This modules provides a few public functions and a public regex to
10 interact with the set of supported compression methods.
11
13 @list = compression_get_list()
14 Returns a list of supported compression methods (sorted
15 alphabetically).
16 compression_is_supported($comp)
18 Returns a boolean indicating whether the give compression method is
19 known and supported.
20 compression_get_property($comp, $property)
22 Returns the requested property of the compression method. Returns
23 undef if either the property or the compression method doesn't
24 exist. Valid properties currently include "file_ext" for the file
25 extension, "default_level" for the default compression level,
26 "comp_prog" for the name of the compression program and
27 "decomp_prog" for the name of the decompression program.
28 This function is deprecated, please switch to one of the new
30 specialized getters instead.
31 compression_guess_from_filename($filename)
33 Returns the compression method that is likely used on the indicated
34 filename based on its file extension.
35 $regex = compression_get_file_extension_regex()
37 Returns a regex that matches a file extension of a file compressed
38 with one of the supported compression methods.
39 $ext = compression_get_file_extension($comp)
41 Return the file extension for the compressor $comp.
42 $comp = compression_get_default()
44 Return the default compression method. It is "xz" unless
45 "compression_set_default" has been used to change it.
46 compression_set_default($comp)
48 Change the default compression method. Errors out if the given
49 compression method is not supported.
50 $level = compression_get_default_level()
52 Return the global default compression level used when compressing
53 data if it has been set, otherwise the default level for the
54 default compressor.
55 It's "9" for "gzip" and "bzip2", "6" for "xz" and "lzma", unless
57 "compression_set_default_level" has been used to change it.
58 compression_set_default_level($level)
60 Change the global default compression level. Passing undef as the
61 level will reset it to the global default compressor specific
62 default, otherwise errors out if the level is not valid (see
63 "compression_is_valid_level").
64 $level = compression_get_level($comp)
66 Return the compression level used when compressing data with a
67 specific compressor. The value returned is the specific compression
68 level if it has been set, otherwise the global default compression
69 level if it has been set, falling back to the specific default
70 compression level.
71 compression_set_level($comp, $level)
73 Change the compression level for a specific compressor. Passing
74 undef as the level will reset it to the specific default compressor
75 level, otherwise errors out if the level is not valid (see
76 "compression_is_valid_level").
77 compression_is_valid_level($level)
79 Returns a boolean indicating whether $level is a valid compression
80 level (it must be either a number between 1 and 9 or "fast" or
81 "best")
82 $threads = compression_get_threads()
84 Return the number of threads to use for compression and
85 decompression.
86 compression_set_threads($threads)
88 Change the threads to use for compression and decompression.
89 Passing "undef" or 0 requests to use automatic mode, based on the
90 current CPU cores on the system.
91 @exec = compression_get_cmdline_compress($comp)
93 Returns a list ready to be passed to "exec", its first element is
94 the program name for compression and the following elements are
95 parameters for the program.
96 When executed the program will act as a filter between its standard
98 input and its standard output.
99 @exec = compression_get_cmdline_decompress($comp)
101 Returns a list ready to be passed to "exec", its first element is
102 the program name for decompression and the following elements are
103 parameters for the program.
104 When executed the program will act as a filter between its standard
106 input and its standard output.
107
109 Version 2.01 (dpkg 1.21.14)
110 New functions: compression_get_file_extension(),
111 compression_get_level(), compression_set_level(),
112 compression_get_cmdline_compress(),
113 compression_get_cmdline_decompress(), compression_get_threads() and
114 compression_set_threads().
115 Deprecated functions: compression_get_property().
117 Version 2.00 (dpkg 1.20.0)
119 Hide variables: $default_compression, $default_compression_level and
120 $compression_re_file_ext.
121 Version 1.02 (dpkg 1.17.2)
123 New function: compression_get_file_extension_regex()
124 Deprecated variables: $default_compression, $default_compression_level
126 and $compression_re_file_ext
127 Version 1.01 (dpkg 1.16.1)
129 Default compression level is not global any more, it is per compressor
130 type.
131 Version 1.00 (dpkg 1.15.6)
133 Mark the module as public.
1341.21.21 2023-03-28 Dpkg::Compression(3perl)