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Diffstat (limited to 'doc/sqfs2tar.1')
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1 files changed, 22 insertions, 20 deletions
diff --git a/doc/sqfs2tar.1 b/doc/sqfs2tar.1 index a71f603..7d91396 100644 --- a/doc/sqfs2tar.1 +++ b/doc/sqfs2tar.1 @@ -1,22 +1,20 @@ .TH SQFS2TAR "1" "June 2019" "sqfs2tar" "User Commands" .SH NAME -sqfs2tar \- turn a squashfs image into a tar archive +sqfs2tar \- turn a SquashFS image into a tar archive .SH SYNOPSIS .B sqfs2tar [\fI\,OPTIONS\/\fR...] \fI\,<sqfsfile>\/\fR .SH DESCRIPTION -Read a squashfs archive and turn it into a tar archive, written to stdout. - -The idea is to quickly and painlessly turn a squashfs filesystem image into -a tar archive that can then be examined and processed by any tool that can -work on tar archives. +Quickly and painlessly turn a SquashFS filesystem image into a tar archive +that can then be examined and processed by any tool that can work on tar +archives. The resulting archive is written to stdout. .PP Possible options: .TP \fB\-\-subdir\fR, \fB\-d\fR <dir> Unpack the given sub directory instead of the filesystem root. Can be specified more than once to select multiple directories. If only one is specified, it -becomes the new root of node of the archive file system tree. +becomes the new root of the archive filesystem tree. .TP \fB\-\-keep\-as\-dir\fR, \fB\-k\fR If \fB\-\-subdir\fR is used only once, don't make the subdir the archive root, @@ -24,11 +22,11 @@ instead keep it as prefix for all unpacked files. Using \fB\-\-subdir\fR more than once implies \fB\-\-keep\-as\-dir\fR. .TP \fB\-\-no\-xattr\fR, \fB\-X\fR -Discard extended attributes from the squashfs image. The default behavior is -to copy all xattrs attached to squashfs inodes into the resulting tar archive. +Discard extended attributes from the SquashFS image. The default behavior is +to copy all xattrs attached to SquashFS inodes into the resulting tar archive. .TP \fB\-\-no\-skip\fR, \fB\-s\fR -Abort if file cannot be stored in a tar record instead of skipping it. +Abort if a file cannot be stored in a tar record instead of skipping it. .TP \fB\-\-help\fR, \fB\-h\fR Print help text and exit. @@ -36,27 +34,31 @@ Print help text and exit. \fB\-\-version\fR, \fB\-V\fR Print version information and exit. .SH COMPATIBILITY -To be compatible with as many tools as possible, the output format is pre-POSIX -ustar archive using GNU extensions where necessary. This seems to be more -widely supported by many tar programs (besides GNU tar), even more than the -newer POSIX format and PAX extensions. - -It is not possible to store socket files in a tar or pax archive. Also, in the -current implementation, all extended attribuates are lost. +The output format is pre-POSIX ustar using GNU extensions where necessary. +Experimentation determined that this is most widely supported by activeley +used tar implementations (besides GNU tar), even more than the newer POSIX +format with PAX extensions. If any file or directory is encountered that cannot be converted, it is skipped and a warning is written to stderr. Unless the \fB\-\-no\-skip\fR option is set, which aborts processing if a file cannot be converted. + +This is mainly affects socket files which are supported by SquashFS but not by +POSIX tar, GNU tar or PAX. + +Since the tar format contains a sequence of files with absolute names, it has +no direct concept of a tree or an unnamed root node. Consequently, meta data +from the SquashFS root inode is lost. .SH EXAMPLES -Turn a squashfs image into a tar archive: +Turn a SquashFS image into a tar archive: .IP sqfs2tar rootfs.sqfs > rootfs.tar .TP -Turn a squashfs image into a gzip'ed tar archive: +Turn a SquashFS image into a gzip'ed tar archive: .IP sqfs2tar rootfs.sqfs | gzip > rootfs.tar.gz .TP -Turn a squashfs image into an LZMA2 compressed tar archive: +Turn a SquashFS image into an LZMA2 compressed tar archive: .IP sqfs2tar rootfs.sqfs | xz > rootfs.tar.xz .SH SEE ALSO |