Provided by: libsysadm-install-perl_0.48-1_all bug


       Sysadm::Install - Typical installation tasks for system administrators


         use Sysadm::Install qw(:all);

         my $INST_DIR = '/home/me/install/';

         cp("/deliver/someproj.tgz", ".");

            # Write out ...
         blurt("Builder: Mike\nDate: Today\n", "build.dat");

            # Slurp back in ...
         my $data = slurp("build.dat");

            # or edit in place ...
         pie(sub { s/Today/scalar localtime()/ge; $_; }, "build.dat");

         make("test install");

            # run a cmd and tap into stdout and stderr
         my($stdout, $stderr, $exit_code) = tap("ls", "-R");


       Have you ever wished for your installation shell scripts to run reproducibly, without much
       programming fuzz, and even with optional logging enabled? Then give up shell programming,
       use Perl.

       "Sysadm::Install" executes shell-like commands performing typical installation tasks:
       Copying files, extracting tarballs, calling "make".  It has a "fail once and die" policy,
       meticulously checking the result of every operation and calling "die()" immediately if
       anything fails.

       "Sysadm::Install" also supports a dry_run mode, in which it logs everything, but
       suppresses any write actions. Dry run mode is enabled by calling
       Sysadm::Install::dry_run(1). To switch back to normal, call Sysadm::Install::dry_run(0).

       As of version 0.17, "Sysadm::Install" supports a confirm mode, in which it interactively
       asks the user before running any of its functions (just like "rm -i"). confirm mode is
       enabled by calling Sysadm::Install::confirm(1). To switch back to normal, call

       "Sysadm::Install" is fully Log4perl-enabled. To start logging, just initialize
       "Log::Log4perl". "Sysadm::Install" acts as a wrapper class, meaning that file names and
       line numbers are reported from the calling program's point of view.

       "cp($source, $target)"
           Copy a file from $source to $target. "target" can be a directory.  Note that "cp"
           doesn't copy file permissions. If you want the target file to reflect the source
           file's user rights, use "perm_cp()" shown below.

       "mv($source, $target)"
           Move a file from $source to $target. "target" can be a directory.

           Download a file specified by $url and store it under the name returned by

           Untar the tarball in $tarball, which typically adheres to the "someproject-X.XX.tgz"
           convention.  But regardless of whether the archive actually contains a top directory
           "someproject-X.XX", this function will behave if it had one. If it doesn't have one, a
           new directory is created before the unpacking takes place. Unpacks the tarball into
           the current directory, no matter where the tarfile is located.  Please note that if
           you're using a compressed tarball (.tar.gz or .tgz), you'll need IO::Zlib installed.

       "untar_in($tar_file, $dir)"
           Untar the tarball in $tgz_file in directory $dir. Create $dir if it doesn't exist yet.

       "pick($prompt, $options, $default, $opts)"
           Ask the user to pick an item from a displayed list. $prompt is the text displayed,
           $options is a referenc to an array of choices, and $default is the number (starting
           from 1, not 0) of the default item. For example,

               pick("Pick a fruit", ["apple", "pear", "pineapple"], 3);

           will display the following:

               [1] apple
               [2] pear
               [3] pineapple
               Pick a fruit [3]>

           If the user just hits Enter, "pineapple" (the default value) will be returned. Note
           that 3 marks the 3rd element of the list, and is not an index value into the array.

           If the user enters 1, 2 or 3, the corresponding text string ("apple", "pear",
           "pineapple" will be returned by "pick()".

           If the optional $opts hash has "{ tty => 1 }" set, then the user response will be
           expected from the console, not STDIN.

       "ask($prompt, $default, $opts)"
           Ask the user to either hit Enter and select the displayed default or to type in
           another string.

           If the optional $opts hash has "{ tty => 1 }" set, then the user response will be
           expected from the console, not STDIN.

           Create a directory of arbitrary depth, just like "File::Path::mkpath".

           Delete a directory and all of its descendents, just like "rm -rf" in the shell.

           chdir to the given directory. If you don't want to have cd() modify the internal
           directory stack (used for subsequent cdback() calls), set the stack_update parameter
           to a false value:

               cd($dir, {stack_update => 0});

           chdir back to the last directory before a previous "cd". If the option "reset" is set,
           it goes all the way back to the beginning of the directory stack, i.e. no matter how
           many cd() calls were made in between, it'll go back to the original directory:

                 # go all the way back
               cdback( { reset => 1 } );

           Call "make" in the shell.

       "pie($coderef, $filename, ...)"
           Simulate "perl -pie 'do something' file". Edits files in-place. Expects a reference to
           a subroutine as its first argument. It will read out the file $filename line by line
           and calls the subroutine setting a localized $_ to the current line. The return value
           of the subroutine will replace the previous value of the line.


               # Replace all 'foo's by 'bar' in test.dat
                   pie(sub { s/foo/bar/g; $_; }, "test.dat");

           Works with one or more file names.

           If the files are known to contain UTF-8 encoded data, and you want it to be
           read/written as a Unicode strings, use the "utf8" option:

               pie(sub { s/foo/bar/g; $_; }, "test.dat", { utf8 => 1 });

       "plough($coderef, $filename, ...)"
           Simulate "perl -ne 'do something' file". Iterates over all lines of all input files
           and calls the subroutine provided as the first argument.


               # Print all lines containing 'foobar'
                   plough(sub { print if /foobar/ }, "test.dat");

           Works with one or more file names.

           If the files are known to contain UTF-8 encoded data, and you want it to be read into
           Unicode strings, use the "utf8" option:

               plough(sub { print if /foobar/ }, "test.dat", { utf8 => 1 });

       "my $data = slurp($file, $options)"
           Slurps in the file and returns a scalar with the file's content. If called without
           argument, data is slurped from STDIN or from any files provided on the command line
           (like <> operates).

           If the file is known to contain UTF-8 encoded data and you want to read it in as a
           Unicode string, use the "utf8" option:

               my $unicode_string = slurp( $file, {utf8 => 1} );

       "blurt($data, $file, $options)"
           Opens a new file, prints the data in $data to it and closes the file.  If
           "$options->{append}" is set to a true value, data will be appended to the file.
           Default is false, existing files will be overwritten.

           If the string is a Unicode string, use the "utf8" option:

               blurt( $unicode_string, $file, {utf8 => 1} );

       "blurt_atomic($data, $file, $options)"
           Write the data in $data to a file $file, guaranteeing that the operation will either
           complete fully or not at all. This is accomplished by first writing to a temporary
           file which is then rename()ed to the target file.

           Unlike in "blurt", there is no $append mode in "blurt_atomic".

           If the string is a Unicode string, use the "utf8" option:

               blurt_atomic( $unicode_string, $file, {utf8 => 1} );

       "($stdout, $stderr, $exit_code) = tap($cmd, @args)"
           Run a command $cmd in the shell, and pass it @args as args.  Capture STDOUT and
           STDERR, and return them as strings. If $exit_code is 0, the command succeeded. If it
           is different, the command failed and $exit_code holds its exit code.

           Please note that "tap()" is limited to single shell commands, it won't work with
           output redirectors ("ls >/tmp/foo" 2>&1).

           In default mode, "tap()" will concatenate the command and args given and create a
           shell command line by redirecting STDERR to a temporary file. "tap("ls", "/tmp")", for
           example, will result in

               'ls' '/tmp' 2>/tmp/sometempfile |

           Note that all commands are protected by single quotes to make sure arguments
           containing spaces are processed as singles, and no globbing happens on wildcards.
           Arguments containing single quotes or backslashes are escaped properly.

           If quoting is undesirable, "tap()" accepts an option hash as its first parameter,

               tap({no_quotes => 1}, "ls", "/tmp/*");

           which will suppress any quoting:

               ls /tmp/* 2>/tmp/sometempfile |

           Or, if you prefer double quotes, use

               tap({double_quotes => 1}, "ls", "/tmp/$VAR");

           wrapping all args so that shell variables are interpolated properly:

               "ls" "/tmp/$VAR" 2>/tmp/sometempfile |

           Another option is "utf8" which runs the command in a terminal set to UTF8.

           Error handling: By default, tap() won't raise an error if the command's return code is
           nonzero, indicating an error reported by the shell. If bailing out on errors is
           requested to avoid return code checking by the script, use the raise_error option:

               tap({raise_error => 1}, "ls", "doesn't exist");

           In DEBUG mode, "tap" logs the entire stdout/stderr output, which can get too verbose
           at times. To limit the number of bytes logged, use the "stdout_limit" and
           "stderr_limit" options

               tap({stdout_limit => 10}, "echo", "123456789101112");

       "$quoted_string = qquote($string, [$metachars])"
           Put a string in double quotes and escape all sensitive characters so there's no
           unwanted interpolation.  E.g., if you have something like

              print "foo!\n";

           and want to put it into a double-quoted string, it will look like

               "print \"foo!\\n\""

           Sometimes, not only backslashes and double quotes need to be escaped, but also the
           target environment's meta chars. A string containing

               print "$<\n";

           needs to have the '$' escaped like

               "print \"\$<\\n\";"

           if you want to reuse it later in a shell context:

               $ perl -le "print \"\$<\\n\";"

           "qquote()" supports escaping these extra characters with its second, optional
           argument, consisting of a string listing  all escapable characters:

               my $script  = 'print "$< rocks!\\n";';
               my $escaped = qquote($script, '!$'); # Escape for shell use
               system("perl -e $escaped");

               => 1212 rocks!

           And there's a shortcut for shells: By specifying ':shell' as the metacharacters
           string, qquote() will actually use '!$`'.

           For example, if you wanted to run the perl code

               print "foobar\n";


               perl -e ...

           on a box via ssh, you would use

               use Sysadm::Install qw(qquote);

               my $cmd = 'print "foobar!\n"';
                  $cmd = "perl -e " . qquote($cmd, ':shell');
                  $cmd = "ssh somehost " . qquote($cmd, ':shell');

               print "$cmd\n";

           and get

               ssh somehost "perl -e \"print \\\"foobar\\\!\\\\n\\\"\""

           which runs on "somehost" without hickup and prints "foobar!".

           Sysadm::Install comes with a script "one-liner" (installed in bin), which takes
           arbitrary perl code on STDIN and transforms it into a one-liner:

               $ one-liner
               Type perl code, terminate by CTRL-D
               print "hello\n";
               print "world\n";
               perl -e "print \"hello\\n\"; print \"world\\n\"; "

       "$quoted_string = quote($string, [$metachars])"
           Similar to "qquote()", just puts a string in single quotes and escapes what needs to
           be escaped.

           Note that shells typically don't support escaped single quotes within single quotes,
           which means that

               $ echo 'foo\'bar'

           is invalid and the shell waits until it finds a closing quote.  Instead, there is an
           evil trick which gives the desired result:

               $ echo 'foo'\''bar'  # foo, single quote, \, 2 x single quote, bar

           It uses the fact that shells interpret back-to-back strings as one.  The construct
           above consists of three back-to-back strings:

               (1) 'foo'
               (2) '
               (3) 'bar'

           which all get concatenated to a single


           If you call "quote()" with $metachars set to ":shell", it will perform that magic
           behind the scenes:

               print quote("foo'bar");
                 # prints: 'foo'\''bar'

       "perm_cp($src, $dst, ...)"
           Read the $src file's user permissions and modify all $dst files to reflect the same

       "owner_cp($src, $dst, ...)"
           Read the $src file/directory's owner uid and group gid and apply it to $dst.

           For example: copy uid/gid of the containing directory to a file therein:

               use File::Basename;

               owner_cp( dirname($file), $file );

           Usually requires root privileges, just like chown does.

       "$perms = perm_get($filename)"
           Read the $filename's user permissions and owner/group.  Returns an array ref to be
           used later when calling "perm_set($filename, $perms)".

       "perm_set($filename, $perms)"
           Set file permissions and owner of $filename according to $perms, which was previously
           acquired by calling "perm_get($filename)".

           Run a shell command via "system()" and die() if it fails. Also works with a list of
           arguments, which are then interpreted as program name plus arguments, just like
           "system()" does it.

       "hammer($cmd, $arg, ...)"
           Run a command in the shell and simulate a user hammering the ENTER key to accept
           defaults on prompts.

       "say($text, ...)"
           Alias for "print ..., "\n"", just like Perl6 is going to provide it.

           Check if the current script is running as root. If yes, continue. If not, restart the
           current script with all command line arguments is restarted under sudo:

               sudo scriptname args ...

           Make sure to call this before any @ARGV-modifying functions like "getopts()" have
           kicked in.

           Search all directories in $PATH (the ENV variable) for an executable named $program
           and return the full path of the first hit. Returns "undef" if the program can't be

           Opens a file handle to read the output of the following process:

               cd $dir; find ./ -xdev -print0 | cpio -o0 |

           This can be used to capture a file system structure.

           Opens a file handle to write to a

               | (cd $dir; cpio -i0)

           process to restore a file system structure. To be used in conjunction with

       "pipe_copy($in, $out, [$bufsize])"
           Reads from $in and writes to $out, using sysread and syswrite. The buffer size used
           defaults to 4096, but can be set explicitly.

       "snip($data, $maxlen)"
           Format the data string in $data so that it's only (roughly) $maxlen characters long
           and only contains printable characters.

           If $data is longer than $maxlen, it will be formatted like


           indicating the length of the original string, the beginning, the end, and the number
           of 'snipped' characters.

           If $data is shorter than $maxlen, it will be returned unmodified (except for
           unprintable characters replaced, see below).

           If $data contains unprintable character's they are replaced by "." (the dot).

       "password_read($prompt, $opts)"
           Reads in a password to be typed in by the user in noecho mode.  A call to
           password_read("password: ") results in

               password: ***** (stars aren't actually displayed)

           This function will switch the terminal back into normal mode after the user hits the
           'Return' key.

           If the optional $opts hash has "{ tty => 1 }" set, then the prompt will be redirected
           to the console instead of STDOUT.

           Format the time in a human-readable way, less wasteful than the 'scalar localtime'

               print nice_time(), "\n";
                 # 2007/04/01 10:51:24

           It uses the system time by default, but it can also accept epoch seconds:

               print nice_time(1170000000), "\n";
                 # 2007/01/28 08:00:00

           It uses localtime() under the hood, so the outcome of the above will depend on your
           local time zone setting.

       "def_or($foo, $default)"
           Perl-5.9 added the //= construct, which helps assigning values to undefined variables.
           Instead of writing

               if(!defined $foo) {
                   $foo = $default;

           you can just write

               $foo //= $default;

           However, this is not available on older perl versions (although there's source filter
           solutions). Often, people use

               $foo ||= $default;

           instead which is wrong if $foo contains a value that evaluates as false.  So
           Sysadm::Install, the everything-and-the-kitchen-sink under the CPAN modules, provides
           the function "def_or()" which can be used like

               def_or($foo, $default);

           to accomplish the same as

               $foo //= $default;

           How does it work, how does $foo get a different value, although it's apparently passed
           in by value? Modifying $_[0] within the subroutine is an old Perl trick to do exactly

           Check if the given string has the utf8 flag turned on. Works just like's
           is_utf8() function, except that it silently returns a false if Encode isn't available,
           for example when an ancient perl without proper utf8 support is used.

           Check if we're using a perl with proper utf8 support, by verifying the
           module is available for loading.

           Return the path to the home directory of the current user.


       Mike Schilli, <>


       Copyright (C) 2004-2007 by Mike Schilli

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of
       Perl 5 you may have available.