From: François Pinard Date: Wed, 16 Nov 1994 02:52:03 +0000 (+0000) Subject: *** empty log message *** X-Git-Url: https://git.dogcows.com/gitweb?a=commitdiff_plain;h=d983432a91e4638986afe092f1f62ca4dafcac67;p=chaz%2Ftar *** empty log message *** --- diff --git a/doc/tar.texi b/doc/tar.texi index 7ed5fa4..8467f2b 100644 --- a/doc/tar.texi +++ b/doc/tar.texi @@ -590,6 +590,90 @@ argument for @samp{-f}, and @samp{-v} does not have a corresponding argument. The modern syntax---@samp{tar -c -v -b 20 -f /dev/rmt0}---is clearer. +@chapter Basic @code{tar} Operations + +This chapter describes the basic operations supported by the @code{tar} +program. A given invocation of @code{tar} will do exactly one of these +operations. + +@section Creating a New Archive + +The @samp{--create} (@code{-c}) option causes @code{tar} to create a new +archive. The files to be archived are then named on the command line. +Each file will be added to the archive with a member name exactly the +same as the name given on the command line. (When you give an absolute +file name @code{tar} actually modifies it slightly, @ref{Absolute +Paths}.) If you list no files to be archived, then an empty archive is +created. + +If there are two many files to conveniently list on the command line, +you can list the names in a file, and @code{tar} will read that file. +@xref{Reading Names from a File}. + +If you name a directory, then @code{tar} will archive not only the +directory, but all its contents, recursively. For example, if you name +@file{/}, then @code{tar} will archive the entire filesystem. + +Do not use the option to add files to an existing archive; it will +delete the archive and write a new one. Use @samp{--append} instead. +(@xref{Adding to an Existing Archive}.) + +There are various ways of causing @code{tar} to skip over some files, +and not archive them. @xref{Specifying Names to @code{tar}}. + +@section Adding to an Existing Archive + +The @samp{--append} (@code{-r}) option will case @code{tar} to add new +files to an existing archive. It interprets file names and member names +in exactly the same manner as @samp{--create}. Nothing happens if you +don't list any names. + +This option never deletes members. If a new member is added under the +same name as an existing member, then both will be in the archive, with +the new member after the old one. For information on how this affects +reading the archive, @ref{Multiple Members with the Same Name}. + +This operation cannot be performed on some tape drives, unfortunately, +due to deficiencies in the formats thoes tape drives use. + +@section Combining Archives + +The @samp{--catenate} (or @code{--concatenate}, or @code{-A}) causes +@code{tar} to add the contents of several archives to an existing +archive. + +Name the archives to be catenated on the command line. (Nothing happens +if you don't list any.) The members, and their member names, will be +copied verbatim from those archives. If this causes multiple members to +have the same name, it does not delete either; all the members with the +same name coexist. For information on how this affects reading the +archive, @ref{Multiple Members with the Same Name}. + +You must use this option to concatenate archives. If you just combine +them with @code{cat}, the result will not be a valid @code{tar} format +archive. + +This operation cannot be performed on some tape drives, unfortunately, +due to deficiencies in the formats thoes tape drives use. + +@section Removing Archive Members + +You can use the @samp{--delete} option to remove members from an +archive. Name the members on the command line to be deleted. This +option will rewrite the archive; because of this, it does not work on +tape drives. If you list no members to be deleted, nothing happens. + +@section Listing Archive Members + +The @samp{--list} (@samp{-t}) option will list the names of members of +the archive. Name the members to be listed on the command line (to +modify the way these names are interpreted, @pxref{Specifying Names to +@code{tar}}). If you name no members, then @samp{--list} will list the +names of all the members of the archive. + +To see more th + + @chapter Specifying Names to @code{tar} When specifying the names of files or members to @code{tar}, it by @@ -645,8 +729,85 @@ If you only want @code{tar} make the date comparison on the basis of the actual contents of the file's modification, then use the @samp{--newer-mtime=@var{date}} option. -You should not depend on this option for making incremental dumps. To -learn how to use @code{tar} to make backups, @ref{Making Backups}. +You should never use this option for making incremental dumps. To learn +how to use @code{tar} to make backups, @ref{Making Backups}. + +@section Crossing Filesystem Boundaries + +The @samp{--one-file-system} option causes @code{tar} to modify its +normal behavior in archiving the contents of directories. If a file in +a directory is not on the same filesystem as the directory itself +(because it is a mounted filesystem in its own right), then @code{tar} +will not archive that file, or (if it is a directory itself) anything +beneath it. + +This does not necessarily limit @code{tar} to only archiving the +contents of a single filesystem, because all files named on the command +line (or through the @samp{--files-from} option) will always be +archived. + +@chapter Changing the Names of Members when Archiing + +@section Changing Directory + +The @samp{--directory=@var{directory}} (@samp{-C @var{directory}}) +option causes @code{tar} to change its current working directory to +@var{directory}. Unlike most options, this one is processed at the +point it occurs within the list of files to be processed. Consider the +following command: +@example +tar --create --file=foo.tar -C /etc passwd hosts -C /lib libc.a +@end example + +This command will place the files @file{/etc/passwd}, @file{/etc/hosts}, +and @file{/lib/libc.a} into the archive. However, the names of the +archive members will be exactly what they were on the command line: +@file{passwd}, @file{hosts}, and @file{libc.a}. The @samp{--directory} +option is frequently used to make the archive independent of the +original name of the directory holding the files. + +Note that @samp{--directory} options are interpreted consecutively. If +@samp{--directory} option specifies a relative pathname, it is +interpreted relative to the then current directory, which might not be +the same as the original current working directory of @code{tar}, due to +a previous @samp{--directory} option. + +When using @samp{--files-from} (@pxref{Reading Names from a File}), you +can put @samp{-C} options in the file list. Unfortunately, you cannot +put @samp{--directory} options in the file list. (This interpretation +can be disabled by using the @samp{--null} option.) + +@section Absolute Path Names + +When @code{tar} extracts archive members from an archive, it strips any +leading slashes (@code{/}) from the member name. This causes absolute +member names in the archive to be treated as relative file names. This +allows you to have such members extracted wherever you want, instead of +being restricted to extracting the member in the exact directory named +in the archive. For example, if the archive member has the name +@file{/etc/passwd}, @code{tar} will extract it as if the name were +really @file{etc/passwd}. + +Other @code{tar} programs do not do this. As a result, if you create an +archive whose member names start with a slash, they will be difficult +for other people with an inferior @code{tar} program to use. Therefore, +GNU @code{tar} also strips leading slashes from member names when +putting members into the archive. For example, if you ask @code{tar} to +add the file @file{/bin/ls} to an archive, it will do so, but the member +name will be @file{bin/ls}. + +If you use the @samp{--absolute-paths} option, @code{tar} will do +neither of these transformations. + +@section Symbolic Links + +Normally, when @code{tar} archives a symbolic link, it writes a record +to the archive naming the target of the link. In that way, the +@code{tar} archive is a faithful record of the filesystem contents. +However, if you want @code{tar} to actually dump the contents of the +target of the symbolic link, then use the @samp{--dereference} option. + + XXXX MIB XXXX