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.IX Title "IO::FILE=IO(0X81D9F0) 1"
.TH IO::FILE=IO(0X81D9F0) 1 "2015-11-09" "perl v5.20.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
stow \- software package installation manager
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
stow [ options ] package ...
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This manual page describes \s-1GNU\s0 Stow 2.2.2, a program for managing
the installation of software packages. This is not the definitive
documentation for stow; for that, see the info manual.
.PP
Stow is a tool for managing the installation of multiple software
packages in the same run-time directory tree. One historical
difficulty of this task has been the need to administer, upgrade,
install, and remove files in independent packages without confusing
them with other files sharing the same filesystem space. For instance,
it is common to install Perl and Emacs in \fI/usr/local\fR.  When one
does so, one winds up (as of Perl 4.036 and Emacs 19.22) with the
following files in \fI/usr/local/man/man1\fR: \fIa2p.1\fR; \fIctags.1\fR;
\&\fIemacs.1\fR; \fIetags.1\fR; \fIh2ph.1\fR; \fIperl.1\fR; and \fIs2p.1\fR.  Now
suppose it's time to uninstall Perl. Which man pages get removed?
Obviously \fIperl.1\fR is one of them, but it should not be the
administrator's responsibility to memorize the ownership of individual
files by separate packages.
.PP
The approach used by Stow is to install each package into its own
tree, then use symbolic links to make it appear as though the files
are installed in the common tree. Administration can be performed in
the package's private tree in isolation from clutter from other
packages.  Stow can then be used to update the symbolic links. The
structure of each private tree should reflect the desired structure in
the common tree; i.e. (in the typical case) there should be a \fIbin\fR
directory containing executables, a \fIman/man1\fR directory containing
section 1 man pages, and so on.
.PP
Stow was inspired by Carnegie Mellon's Depot program, but is
substantially simpler and safer. Whereas Depot required database files
to keep things in sync, Stow stores no extra state between runs, so
there's no danger (as there was in Depot) of mangling directories when
file hierarchies don't match the database. Also unlike Depot, Stow
will never delete any files, directories, or links that appear in a
Stow directory (e.g., \fI/usr/local/stow/emacs\fR), so it's always
possible to rebuild the target tree (e.g., \fI/usr/local\fR).
.SH "TERMINOLOGY"
.IX Header "TERMINOLOGY"
A \*(L"package\*(R" is a related collection of files and directories that
you wish to administer as a unit \*(-- e.g., Perl or Emacs \*(-- and that
needs to be installed in a particular directory structure \*(-- e.g.,
with \fIbin\fR, \fIlib\fR, and \fIman\fR subdirectories.
.PP
A \*(L"target directory\*(R" is the root of a tree in which one or more
packages wish to \fBappear\fR to be installed. A common, but by no means
the only such location is \fI/usr/local\fR.  The examples in this manual
page will use \fI/usr/local\fR as the target directory.
.PP
A \*(L"stow directory\*(R" is the root of a tree containing separate
packages in private subtrees. When Stow runs, it uses the current
directory as the default stow directory. The examples in this manual
page will use \fI/usr/local/stow\fR as the stow directory, so that
individual packages will be, for example, \fI/usr/local/stow/perl\fR and
\&\fI/usr/local/stow/emacs\fR.
.PP
An \*(L"installation image\*(R" is the layout of files and directories
required by a package, relative to the target directory. Thus, the
installation image for Perl includes: a \fIbin\fR directory containing
\&\fIperl\fR and \fIa2p\fR (among others); an \fIinfo\fR directory containing
Texinfo documentation; a \fIlib/perl\fR directory containing Perl
libraries; and a \fIman/man1\fR directory containing man pages.
.PP
A \*(L"package directory\*(R" is the root of a tree containing the
installation image for a particular package. Each package directory
must reside in a stow directory \*(-- e.g., the package directory
\&\fI/usr/local/stow/perl\fR must reside in the stow directory
\&\fI/usr/local/stow\fR.  The \*(L"name\*(R" of a package is the name of its
directory within the stow directory \*(-- e.g., \fIperl\fR.
.PP
Thus, the Perl executable might reside in
\&\fI/usr/local/stow/perl/bin/perl\fR, where \fI/usr/local\fR is the target
directory, \fI/usr/local/stow\fR is the stow directory,
\&\fI/usr/local/stow/perl\fR is the package directory, and \fIbin/perl\fR
within is part of the installation image.
.PP
A \*(L"symlink\*(R" is a symbolic link. A symlink can be \*(L"relative\*(R" or
\&\*(L"absolute\*(R". An absolute symlink names a full path; that is, one
starting from \fI/\fR.  A relative symlink names a relative path; that
is, one not starting from \fI/\fR.  The target of a relative symlink is
computed starting from the symlink's own directory.  Stow only creates
relative symlinks.
.SH "OPTIONS"
.IX Header "OPTIONS"
The stow directory is assumed to be the value of the \f(CW\*(C`STOW_DIR\*(C'\fR
environment variable or if unset the current directory, and the target
directory is assumed to be the parent of the current directory (so it
is typical to execute \fIstow\fR from the directory \fI/usr/local/stow\fR).
Each \fIpackage\fR given on the command line is the name of a package in
the stow directory (e.g., \fIperl\fR).  By default, they are installed
into the target directory (but they can be deleted instead using
\&\f(CW\*(C`\-D\*(C'\fR).
.IP "\-n" 4
.IX Item "-n"
.PD 0
.IP "\-\-no" 4
.IX Item "--no"
.PD
Do not perform any operations that modify the filesystem; merely show
what would happen.
.IP "\-d \s-1DIR\s0" 4
.IX Item "-d DIR"
.PD 0
.IP "\-\-dir=DIR" 4
.IX Item "--dir=DIR"
.PD
Set the stow directory to \f(CW\*(C`DIR\*(C'\fR instead of the current directory.
This also has the effect of making the default target directory be the
parent of \f(CW\*(C`DIR\*(C'\fR.
.IP "\-t \s-1DIR\s0" 4
.IX Item "-t DIR"
.PD 0
.IP "\-\-target=DIR" 4
.IX Item "--target=DIR"
.PD
Set the target directory to \f(CW\*(C`DIR\*(C'\fR instead of the parent of the stow
directory.
.IP "\-v" 4
.IX Item "-v"
.PD 0
.IP "\-\-verbose[=N]" 4
.IX Item "--verbose[=N]"
.PD
Send verbose output to standard error describing what Stow is
doing. Verbosity levels are 0, 1, 2, 3, and 4; 0 is the default.
Using \f(CW\*(C`\-v\*(C'\fR or \f(CW\*(C`\-\-verbose\*(C'\fR increases the verbosity by one; using
`\-\-verbose=N' sets it to N.
.IP "\-S" 4
.IX Item "-S"
.PD 0
.IP "\-\-stow" 4
.IX Item "--stow"
.PD
Stow the packages that follow this option into the target directory.
This is the default action and so can be omitted if you are only
stowing packages rather than performing a mixture of
stow/delete/restow actions.
.IP "\-D" 4
.IX Item "-D"
.PD 0
.IP "\-\-delete" 4
.IX Item "--delete"
.PD
Unstow the packages that follow this option from the target directory rather
than installing them.
.IP "\-R" 4
.IX Item "-R"
.PD 0
.IP "\-\-restow" 4
.IX Item "--restow"
.PD
Restow packages (first unstow, then stow again). This is useful
for pruning obsolete symlinks from the target tree after updating
the software in a package.
.IP "\-\-adopt" 4
.IX Item "--adopt"
\&\fBWarning!\fR  This behaviour is specifically intended to alter the
contents of your stow directory.  If you do not want that, this option
is not for you.
.Sp
When stowing, if a target is encountered which already exists but is a
plain file (and hence not owned by any existing stow package), then
normally Stow will register this as a conflict and refuse to proceed.
This option changes that behaviour so that the file is moved to the
same relative place within the package's installation image within the
stow directory, and then stowing proceeds as before.  So effectively,
the file becomes adopted by the stow package, without its contents
changing.
.IP "\-\-no\-folding" 4
.IX Item "--no-folding"
Disable folding of newly stowed directories when stowing, and
refolding of newly foldable directories when unstowing.
.IP "\-\-ignore=REGEX" 4
.IX Item "--ignore=REGEX"
Ignore files ending in this Perl regex.
.IP "\-\-defer=REGEX" 4
.IX Item "--defer=REGEX"
Don't stow files beginning with this Perl regex if the file is already
stowed to another package.
.IP "\-\-override=REGEX" 4
.IX Item "--override=REGEX"
Force stowing files beginning with this Perl regex if the file is
already stowed to another package.
.IP "\-V" 4
.IX Item "-V"
.PD 0
.IP "\-\-version" 4
.IX Item "--version"
.PD
Show Stow version number, and exit.
.IP "\-h" 4
.IX Item "-h"
.PD 0
.IP "\-\-help" 4
.IX Item "--help"
.PD
Show Stow command syntax, and exit.
.SH "INSTALLING PACKAGES"
.IX Header "INSTALLING PACKAGES"
The default action of Stow is to install a package. This means
creating symlinks in the target tree that point into the package tree.
Stow attempts to do this with as few symlinks as possible; in other
words, if Stow can create a single symlink that points to an entire
subtree within the package tree, it will choose to do that rather than
create a directory in the target tree and populate it with symlinks.
.PP
For example, suppose that no packages have yet been installed in
\&\fI/usr/local\fR; it's completely empty (except for the \fIstow\fR
subdirectory, of course). Now suppose the Perl package is installed.
Recall that it includes the following directories in its installation
image: \fIbin\fR; \fIinfo\fR; \fIlib/perl\fR; \fIman/man1\fR.  Rather than
creating the directory \fI/usr/local/bin\fR and populating it with
symlinks to \fI../stow/perl/bin/perl\fR and \fI../stow/perl/bin/a2p\fR (and
so on), Stow will create a single symlink, \fI/usr/local/bin\fR, which
points to \fIstow/perl/bin\fR.  In this way, it still works to refer to
\&\fI/usr/local/bin/perl\fR and \fI/usr/local/bin/a2p\fR, and fewer symlinks
have been created. This is called \*(L"tree folding\*(R", since an entire
subtree is \*(L"folded\*(R" into a single symlink.
.PP
To complete this example, Stow will also create the symlink
\&\fI/usr/local/info\fR pointing to \fIstow/perl/info\fR; the symlink
\&\fI/usr/local/lib\fR pointing to \fIstow/perl/lib\fR; and the symlink
\&\fI/usr/local/man\fR pointing to \fIstow/perl/man\fR.
.PP
Now suppose that instead of installing the Perl package into an empty
target tree, the target tree is not empty to begin with. Instead, it
contains several files and directories installed under a different
system-administration philosophy. In particular, \fI/usr/local/bin\fR
already exists and is a directory, as are \fI/usr/local/lib\fR and
\&\fI/usr/local/man/man1\fR.  In this case, Stow will descend into
\&\fI/usr/local/bin\fR and create symlinks to \fI../stow/perl/bin/perl\fR and
\&\fI../stow/perl/bin/a2p\fR (etc.), and it will descend into
\&\fI/usr/local/lib\fR and create the tree-folding symlink \fIperl\fR pointing
to \fI../stow/perl/lib/perl\fR, and so on. As a rule, Stow only descends
as far as necessary into the target tree when it can create a
tree-folding symlink.
.PP
The time often comes when a tree-folding symlink has to be undone
because another package uses one or more of the folded subdirectories
in its installation image. This operation is called \*(L"splitting open\*(R"
a folded tree. It involves removing the original symlink from the
target tree, creating a true directory in its place, and then
populating the new directory with symlinks to the newly-installed
package \fBand\fR to the old package that used the old symlink. For
example, suppose that after installing Perl into an empty
\&\fI/usr/local\fR, we wish to install Emacs.  Emacs's installation image
includes a \fIbin\fR directory containing the \fIemacs\fR and \fIetags\fR
executables, among others. Stow must make these files appear to be
installed in \fI/usr/local/bin\fR, but presently \fI/usr/local/bin\fR is a
symlink to \fIstow/perl/bin\fR.  Stow therefore takes the following
steps: the symlink \fI/usr/local/bin\fR is deleted; the directory
\&\fI/usr/local/bin\fR is created; links are made from \fI/usr/local/bin\fR to
\&\fI../stow/emacs/bin/emacs\fR and \fI../stow/emacs/bin/etags\fR; and links
are made from \fI/usr/local/bin\fR to \fI../stow/perl/bin/perl\fR and
\&\fI../stow/perl/bin/a2p\fR.
.PP
When splitting open a folded tree, Stow makes sure that the symlink
it is about to remove points inside a valid package in the current stow
directory.
.SS "Stow will never delete anything that it doesn't own."
.IX Subsection "Stow will never delete anything that it doesn't own."
Stow \*(L"owns\*(R" everything living in the target tree that points into a
package in the stow directory. Anything Stow owns, it can recompute if
lost. Note that by this definition, Stow doesn't \*(L"own\*(R" anything
\&\fBin\fR the stow directory or in any of the packages.
.PP
If Stow needs to create a directory or a symlink in the target tree
and it cannot because that name is already in use and is not owned by
Stow, then a conflict has arisen. See the \*(L"Conflicts\*(R" section in the
info manual.
.SH "DELETING PACKAGES"
.IX Header "DELETING PACKAGES"
When the \f(CW\*(C`\-D\*(C'\fR option is given, the action of Stow is to delete a
package from the target tree. Note that Stow will not delete anything
it doesn't \*(L"own\*(R". Deleting a package does \fBnot\fR mean removing it from
the stow directory or discarding the package tree.
.PP
To delete a package, Stow recursively scans the target tree, skipping
over the stow directory (since that is usually a subdirectory of the
target tree) and any other stow directories it encounters (see
\&\*(L"Multiple stow directories\*(R" in the info manual). Any symlink it
finds that points into the package being deleted is removed. Any
directory that contained only symlinks to the package being deleted is
removed. Any directory that, after removing symlinks and empty
subdirectories, contains only symlinks to a single other package, is
considered to be a previously \*(L"folded\*(R" tree that was \*(L"split open.\*(R"
Stow will re-fold the tree by removing the symlinks to the surviving
package, removing the directory, then linking the directory back to
the surviving package.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
The full documentation for \fIstow\fR is maintained as a Texinfo manual.
If the \fIinfo\fR and \fIstow\fR programs are properly installed at your site, the command
.PP
.Vb 1
\&    info stow
.Ve
.PP
should give you access to the complete manual.
.SH "BUGS"
.IX Header "BUGS"
Please report bugs in Stow using the Debian bug tracking system.
.PP
Currently known bugs include:
.IP "\(bu" 4
The empty-directory problem.
.Sp
If package \fIfoo\fR includes an empty directory \*(-- say, \fIfoo/bar\fR \*(--
then if no other package has a \fIbar\fR subdirectory, everything's fine.
If another stowed package \fIquux\fR, has a \fIbar\fR subdirectory, then
when stowing, \fItargetdir/bar\fR will be \*(L"split open\*(R" and the contents
of \fIquux/bar\fR will be individually stowed.  So far, so good. But when
unstowing \fIquux\fR, \fItargetdir/bar\fR will be removed, even though
\&\fIfoo/bar\fR needs it to remain.  A workaround for this problem is to
create a file in \fIfoo/bar\fR as a placeholder. If you name that file
\&\fI.placeholder\fR, it will be easy to find and remove such files when
this bug is fixed.
.IP "\(bu" 4
When using multiple stow directories (see \*(L"Multiple stow directories\*(R"
in the info manual), Stow fails to \*(L"split open\*(R" tree-folding symlinks
(see \*(L"Installing packages\*(R" in the info manual) that point into a stow
directory which is not the one in use by the current Stow
command. Before failing, it should search the target of the link to
see whether any element of the path contains a \fI.stow\fR file. If it
finds one, it can \*(L"learn\*(R" about the cooperating stow directory to
short-circuit the \fI.stow\fR search the next time it encounters a
tree-folding symlink.
.SH "AUTHOR"
.IX Header "AUTHOR"
This man page was originally constructed by Charles Briscoe-Smith from
parts of Stow's info manual, and then converted to \s-1POD\s0 format by Adam
Spiers.  The info manual contains the following notice, which, as it
says, applies to this manual page, too.  The text of the section
entitled \*(L"\s-1GNU\s0 General Public License\*(R" can be found in the file
\&\fI/usr/share/common\-licenses/GPL\fR on any Debian GNU/Linux system.  If
you don't have access to a Debian system, or the \s-1GPL\s0 is not there,
write to the Free Software Foundation, Inc., 59 Temple Place, Suite
330, Boston, \s-1MA, 02111\-1307, USA.\s0
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (C)
1993, 1994, 1995, 1996 by Bob Glickstein <bobg+stow@zanshin.com>;
2000, 2001 by Guillaume Morin;
2007 by Kahlil Hodgson;
2011 by Adam Spiers;
and others.
.PP
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
.PP
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the section entitled \*(L"\s-1GNU\s0 General Public License\*(R" is included with the
modified manual, and provided that the entire resulting derived work
is distributed under the terms of a permission notice identical to
this one.
.PP
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Free Software Foundation.