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docs: Obsolete HACKING file, move content into guestfs(3) man page.
Add a new section called "EXTENDING LIBGUESTFS" to the guestfs manual page which contains all the information previously in "HACKING".
This commit is contained in:
Richard W.M. Jones
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HACKING
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HACKING
@@ -1,258 +1,2 @@
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PLEASE LOOK AT THE TOP OF EACH FILE BEFORE EDITING TO SEE WHETHER IT
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IS AUTOMATICALLY GENERATED OR NOT.
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Adding a new action
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----------------------------------------------------------------------
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All action functions are generated automatically, so there are only
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two files you need to edit:
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(1) generator/generator_actions.ml: Add your new action, parameters,
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description, etc. to the big list at the top of this file.
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(2) Edit/create a C file in daemon/ subdirectory which implements your
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'do_action' function. Take a look at one of the numerous examples
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there.
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Formatting
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----------------------------------------------------------------------
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Try to use GNU / Emacs default formatting, following the convention
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used elsewhere in the source.
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Please make sure that the code compiles without warnings.
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Please test any changes.
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Useful targets:
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make syntax-check Checks the syntax of the C code.
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make check Runs the test suite.
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Enable warnings, and fix any you find:
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./configure --enable-gcc-warnings
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Code indentation
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----------------------------------------------------------------------
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Our C source code generally adheres to some basic code-formatting
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conventions. The existing code base is not totally consistent on this
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front, but we do prefer that contributed code be formatted similarly.
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In short, use spaces-not-TABs for indentation, use 2 spaces for each
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indentation level, and other than that, follow the K&R style.
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If you use Emacs, add the following to one of one of your start-up files
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(e.g., ~/.emacs), to help ensure that you get indentation right:
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;;; In libguestfs, indent with spaces everywhere (not TABs).
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;;; Exceptions: Makefile and ChangeLog modes.
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(add-hook 'find-file-hook
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'(lambda () (if (and buffer-file-name
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(string-match "/libguestfs\\>" (buffer-file-name))
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(not (string-equal mode-name "Change Log"))
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(not (string-equal mode-name "Makefile")))
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(setq indent-tabs-mode nil))))
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;;; When editing C sources in libguestfs, use this style.
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(defun libguestfs-c-mode ()
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"C mode with adjusted defaults for use with libguestfs."
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(interactive)
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(c-set-style "K&R")
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(setq c-indent-level 2)
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(setq c-basic-offset 2))
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(add-hook 'c-mode-hook
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'(lambda () (if (string-match "/libguestfs\\>" (buffer-file-name))
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(libguestfs-c-mode))))
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Directories
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----------------------------------------------------------------------
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appliance/
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The qemu appliance, build scripts and so on.
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capitests/
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Automated tests of the C API. See "Tests" below.
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cat/
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The 'virt-cat', 'virt-filesystems' and 'virt-ls' commands and
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documentation.
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contrib/
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Outside contributions, experimental parts.
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csharp/
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Experimental C# bindings.
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daemon/
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The daemon that runs inside the guest and carries out actions.
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df/
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'virt-df' command and documentation.
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examples/
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The examples.
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fish/
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Guestfish (the command-line program / shell)
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fuse/
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FUSE (userspace filesystem) built on top of libguestfs.
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generator/
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The crucially important generator, used to automatically
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generate large amounts of boilerplate C code for things like
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RPC and bindings.
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haskell/
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Haskell bindings.
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hivex/ [removed in 1.0.85]
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This used to contain the hivex library for reading and
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writing Windows Registry binary hive files. This is now
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available as a separate upstream project.
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images/
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Some guest images to test against. These are gzipped to save
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space. You have to unzip them before use.
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Also contains some files used by the test suite.
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inspector/
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Virtual machine image inspector (virt-inspector).
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java/
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Java bindings.
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m4/
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M4 macros used by autoconf.
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ocaml/
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OCaml bindings.
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php/
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PHP bindings.
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po/
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Translations of simple gettext strings. For translations of
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longer documents, see po-docs/.
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po-docs/
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The build infrastructure and PO files for translations of
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manpages and POD files. Eventually this will be combined
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with the po/ directory, but that is rather complicated.
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perl/
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Perl bindings.
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python/
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Python bindings.
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regressions/
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Regression tests.
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rescue/
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'virt-rescue' command and documentation.
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ruby/
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Ruby bindings.
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tools/
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Command line tools written in Perl (virt-resize and more).
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src/
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Source code to the C library.
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test-tool/
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Interactive qemu/kernel test tool.
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Tests
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----------------------------------------------------------------------
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You can supply zero or as many tests as you want per API call.
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The test environment has 4 block devices:
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/dev/sda 500MB General block device for testing.
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/dev/sdb 50MB /dev/sdb1 is an ext2 filesystem used for testing
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filesystem write operations.
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/dev/sdc 10MB Used in a few tests where 2 block devices are needed.
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/dev/sdd - ISO with fixed content (see images/test.iso).
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To be able to run the tests in a reasonable amount of time, the
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virtual machine and block devices are reused between tests. So don't
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try testing kill_subprocess :-x Between each test we blockdev-setrw,
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umount-all, lvm-remove-all.
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Each test starts with an initial scenario, selected using one of the
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'Init*' expressions, described in generator/generator_types.ml. These
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initialize the disks in a particular way as described. You should not
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assume anything about the previous contents of other disks that are
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not initialized.
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You can add a prerequisite clause to any individual test. This is a
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run-time check, which, if it fails, causes the test to be skipped.
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Useful if testing a command which might not work on all variations of
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libguestfs builds. A test that has prerequisite of 'Always' is run
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unconditionally.
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In addition, packagers can skip individual tests by setting the
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environment variables: eg:
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SKIP_TEST_<CMD>_<NUM>=1 SKIP_TEST_COMMAND_3=1 (skips test #3 of command)
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SKIP_TEST_<CMD>=1 SKIP_TEST_ZEROFREE=1 (skips all zerofree tests)
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and packagers can run only certain tests by setting eg:
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TEST_ONLY="vfs_type zerofree"
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See capitests/tests.c for more details of how these environment
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variables work.
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Debugging
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----------------------------------------------------------------------
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It's a good idea to use guestfish to try out new commands.
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Debugging the daemon is a problem because it runs inside a minimal
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qemu environment. However you can print messages from the daemon, and
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they will show up if you use 'guestfish -v'.
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Patches
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----------------------------------------------------------------------
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Submit patches to the mailing list:
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http://www.redhat.com/mailman/listinfo/libguestfs
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and CC to rjones@redhat.com
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I18N
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----------------------------------------------------------------------
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We support i18n (gettext anyhow) in the library.
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However many messages come from the daemon, and we don't translate
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those at the moment. One reason is that the appliance generally has
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all locale files removed from it, because they take up a lot of space.
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So we'd have to readd some of those, as well as copying our PO files
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into the appliance.
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Debugging messages are never translated, since they are intended for
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the programmers.
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Extended printf
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----------------------------------------------------------------------
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In the daemon code we have created custom printf formatters %Q and %R,
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which are used to do shell quoting.
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%Q => Simple shell quoted string. Any spaces or other shell characters
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are escaped for you.
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%R => Same as %Q except the string is treated as a path which is prefixed
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by the sysroot.
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eg.
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asprintf (&cmd, "cat %R", path);
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==> "cat /sysroot/some\ path\ with\ spaces"
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Note: Do NOT use these when you are passing parameters to the
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command{,r,v,rv}() functions. These parameters do NOT need to be
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quoted because they are not passed via the shell (instead, straight to
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exec). You probably want to use the sysroot_path() function however.
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The contents of this page have moved to the section "EXTENDING LIBGUESTFS"
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in the guestfs(3) man page.
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