OPTIONS Integer suffixes and special values xz file is stored on a medium that measuresĬoncatenation and padding are not allowed with. The padding must consist of null bytes and the size of the padding must be a multiple ofįour bytes. It is possible to insert padding between the concatenated parts or after the last part.
The settings will be scaled down only a little, not all the way down to xz -8. if the limit is only slightly less than the amount required for xz -9, The scaling of the settings is done in steps that don't match the compression This way the operation won't fail unless the limit is Will try to scale the settings down so that the limit is no longer exceeded (except when
If the limit is exceeded when compressing, xz If the specified memory usage limit is exceeded when decompressing, xz will display anĮrror and decompressing the file will fail. memlimit= limit (or -M limit) is shorter to type on the command line. Using these two options outside XZ_DEFAULTS is rarely usefulīecause a single run of xz cannot do both compression and decompression and Limits separately for compression and decompression by using -memlimit-compress= limit and Often it is more convenient to enable the limiter by default by setting the environment The memory usage limiter can be enabled with the command line option -memlimit= limit. Ulimit(1) to limit virtual memory tends to cripple mmap(2)). Memory usage of processes, relying on it wasn't deemed to be flexible enough (e.g. While some operating systems provide ways to limit the To prevent uncomfortable surprises, xz has a built-in memory usage limiter, xz files that require several gigabytes of memory to decompress.Įspecially users of older systems may find the possibility of very large memory usageĪnnoying. For example,ĭecompressing a file created with xz -9 currently requires 65 MiB of memory. The amount of memory that the compressor needed when creating the file. Typically the decompressor needs 5 % to 20 % of The settings used when compressing a file determine the The memory usage of xz varies from a few hundred kilobytes to several gigabytes depending verbose will display an automatically updating progress indicator. This has only limited use since when standard error is a terminal, using Sending SIGINFO or SIGUSR1 to the xz process makes it print progress information to The source file is never removed if the output is written to Once the target file has been successfully closed, the source file is removed unless xzĭoesn't support copying other metadata like access control lists or extended attributes If copying the group fails, the permissions are modified so that the target file doesn'tīecome accessible to users who didn't have permission to access the source file. Permissions, access time, and modification time from the source file to the target file. tlz).Īfter successfully compressing or decompressing the file, xz copies the owner, group,
lzma filesĬOMMAND ALIASES unxz is equivalent to xz -decompress. Xz, unxz, xzcat, lzma, unlzma, lzcat - Compress or decompress.
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