X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=tools%2Fvirt-edit;h=887ef4b64609dad086b13e9e6834a26f4290c459;hp=c133e6a1a5d0691956e5e61f088d3f3c5fc117f8;hb=fb998000e60b32219c2bf839044cff59f499dff1;hpb=9a608a1516bd339dc6d5ebe9952d3bced273c416 diff --git a/tools/virt-edit b/tools/virt-edit index c133e6a..887ef4b 100755 --- a/tools/virt-edit +++ b/tools/virt-edit @@ -1,6 +1,6 @@ #!/usr/bin/perl -w # virt-edit -# Copyright (C) 2009 Red Hat Inc. +# Copyright (C) 2009-2010 Red Hat Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by @@ -40,6 +40,8 @@ virt-edit - Edit a file in a virtual machine virt-edit [--options] disk.img [disk.img ...] file + virt-edit [domname|disk.img] file -e 'expr' + =head1 WARNING You must I use C on live virtual machines. If you do @@ -56,10 +58,18 @@ cases you should look at the L tool. =head1 EXAMPLES +Edit the named files interactively: + virt-edit mydomain /boot/grub/grub.conf virt-edit mydomain /etc/passwd +You can also edit files non-interactively (see +L below). +To change the init default level to 5: + + virt-edit mydomain /etc/inittab -e 's/^id:.*/id:5:initdefault:/' + =head1 OPTIONS =over 4 @@ -82,6 +92,22 @@ Display version number and exit. =cut +my $backup; + +=item B<--backup extension> | B<-b extension> + +Create a backup of the original file I. +The backup has the original filename with C added. + +Usually the first character of C would be a dot C<.> +so you would write: + + virt-edit -b .orig [etc] + +By default, no backup file is made. + +=cut + my $uri; =item B<--connect URI> | B<-c URI> @@ -92,6 +118,36 @@ connect to the default libvirt hypervisor. If you specify guest block devices directly, then libvirt is not used at all. +=cut + +my $format; + +=item B<--format> raw + +Specify the format of disk images given on the command line. If this +is omitted then the format is autodetected from the content of the +disk image. + +If disk images are requested from libvirt, then this program asks +libvirt for this information. In this case, the value of the format +parameter is ignored. + +If working with untrusted raw-format guest disk images, you should +ensure the format is always specified. + +=cut + +my $expr; + +=item B<--expr EXPR> | B<-e EXPR> + +Instead of launching the external editor, non-interactively +apply the Perl expression C to each line in the file. +See L below. + +Be careful to properly quote the expression to prevent it from +being altered by the shell. + =back =cut @@ -99,6 +155,9 @@ at all. GetOptions ("help|?" => \$help, "version" => \$version, "connect|c=s" => \$uri, + "format=s" => \$format, + "expr|e=s" => \$expr, + "backup|b=s" => \$backup, ) or pod2usage (2); pod2usage (1) if $help; if ($version) { @@ -115,9 +174,9 @@ my $filename = pop @ARGV; my $g; if ($uri) { - $g = open_guest (\@ARGV, address => $uri, rw => 1); + $g = open_guest (\@ARGV, address => $uri, rw => 1, format => $format); } else { - $g = open_guest (\@ARGV, rw => 1); + $g = open_guest (\@ARGV, rw => 1, format => $format); } $g->launch (); @@ -133,40 +192,141 @@ my %fses = my $oses = inspect_operating_systems ($g, \%fses); my @roots = keys %$oses; -die __"no root device found in this operating system image" if @roots == 0; die __"multiboot operating systems are not supported by virt-edit" if @roots > 1; my $root_dev = $roots[0]; my $os = $oses->{$root_dev}; mount_operating_system ($g, $os, 0); -my ($fh, $tempname) = tempfile (); +my ($fh_not_used, $tempname) = tempfile (UNLINK => 1); # Allow this to fail in case eg. the file does not exist. $g->download($filename, $tempname); -my $oldctime = (stat ($tempname))[10]; +my $do_upload = $tempname; + +if (!defined $expr) { + # Interactively edit the file. + my $oldctime = (stat ($tempname))[10]; -my $editor = $ENV{EDITOR}; -$editor ||= "vi"; -system ("$editor $tempname") == 0 - or die "edit failed: $editor: $?"; + my $editor = $ENV{EDITOR}; + $editor ||= "vi"; + system ("$editor $tempname") == 0 + or die "edit failed: $editor: $?"; -my $newctime = (stat ($tempname))[10]; + my $newctime = (stat ($tempname))[10]; -if ($oldctime != $newctime) { - $g->upload ($tempname, $filename) + if ($oldctime == $newctime) { + $do_upload = undef; + print __"File not changed.\n"; + } } else { - print __"File not changed.\n"; + my ($fh, $tempout) = tempfile (UNLINK => 1); + + # Apply a Perl expression to the lines of the file. + open IFILE, $tempname or die "$tempname: $!"; + my $lineno = 0; + while () { + $lineno++; + eval $expr; + die if $@; + print $fh $_ or die "print: $!"; + } + close $fh; + + $do_upload = $tempout; } -$g->sync (); -$g->umount_all (); +if (defined $do_upload) { + # Upload to a new file, so if it fails we don't end up with + # a partially written file. Give the new file a completely + # random name so we have only a tiny chance of overwriting + # some existing file. + my $dirname = $filename; + $dirname =~ s{/[^/]+$}{/}; + + my @chars = ('a'..'z', 'A'..'Z', '0'..'9'); + my $newname = $dirname; + foreach (0..7) { + $newname .= $chars[rand @chars]; + } + + $g->upload ($do_upload, $newname); + + # Backup or overwrite? + $g->mv ($filename, "$filename$backup") if defined $backup; + $g->mv ($newname, $filename); + + $g->umount_all (); + $g->sync (); +} undef $g; exit 0; +=head1 NON-INTERACTIVE EDITING + +C normally calls out to C<$EDITOR> (or vi) so +the system administrator can interactively edit the file. + +There are two ways also to use C from scripts in order to +make automated edits to files. (Note that although you I use +C like this, it's less error-prone to write scripts +directly using the libguestfs API and Augeas for configuration file +editing.) + +The first method is to temporarily set C<$EDITOR> to any script or +program you want to run. The script is invoked as C<$EDITOR tmpfile> +and it should update C in place however it likes. + +The second method is to use the C<-e> parameter of C to run +a short Perl snippet in the style of L. For example to +replace all instances of C with C in a file: + + virt-edit domname filename -e 's/foo/bar/' + +The full power of Perl regular expressions can be used (see +L). For example to delete root's password you could do: + + virt-edit domname /etc/passwd -e 's/^root:.*?:/root::/' + +What really happens is that the snippet is evaluated as a Perl +expression for each line of the file. The line, including the final +C<\n>, is passed in C<$_> and the expression should update C<$_> or +leave it unchanged. + +To delete a line, set C<$_> to the empty string. For example, to +delete the C user account from the password file you can do: + + virt-edit mydomain /etc/passwd -e '$_ = "" if /^apache:/' + +To insert a line, prepend or append it to C<$_>. However appending +lines to the end of the file is rather difficult this way since there +is no concept of "last line of the file" - your expression just +doesn't get called again. You might want to use the first method +(setting C<$EDITOR>) if you want to do this. + +The variable C<$lineno> contains the current line number. +As is traditional, the first line in the file is number C<1>. + +The return value from the expression is ignored, but the expression +may call C in order to abort the whole program, leaving the +original file untouched. + +Remember when matching the end of a line that C<$_> may contain the +final C<\n>, or (for DOS files) C<\r\n>, or if the file does not end +with a newline then neither of these. Thus to match or substitute +some text at the end of a line, use this regular expression: + + /some text(\r?\n)?$/ + +Alternately, use the perl C function, being careful not to +chomp C<$_> itself (since that would remove all newlines from the +file): + + my $m = $_; chomp $m; $m =~ /some text$/ + =head1 ENVIRONMENT VARIABLES =over 4 @@ -180,6 +340,13 @@ If not set, C is used. =back +=head1 SHELL QUOTING + +Libvirt guest names can contain arbitrary characters, some of which +have meaning to the shell such as C<#> and space. You may need to +quote or escape these characters on the command line. See the shell +manual page L for details. + =head1 SEE ALSO L, @@ -188,7 +355,9 @@ L, L, L, L, -L. +L, +L, +L. =head1 AUTHOR @@ -196,7 +365,7 @@ Richard W.M. Jones L =head1 COPYRIGHT -Copyright (C) 2009 Red Hat Inc. +Copyright (C) 2009-2010 Red Hat Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by