Scriptalicious(3pm) User Contributed Perl Documentation Scriptalicious(3pm)
NAME
Scriptalicious - Make scripts more delicious to SysAdmins
SYNOPSIS
use Scriptalicious
-progname => "pu";
our $VERSION = "1.00";
my $url = ".";
getopt getconf("u|url" => $url);
run("echo", "doing something with $url");
my $output = capture("svn", "info", $url);
__END__
=head1 NAME
pu - an uncarved block of wood
=head1 SYNOPSIS
pu [options] arguments
=head1 DESCRIPTION
This script's function is to be a blank example that many
great and simple scripts may be built upon.
Remember, you cannot carve rotten wood.
=head1 COMMAND LINE OPTIONS
=over
=item B<-h, --help>
Display a program usage screen and exit.
=item B<-V, --version>
Display program version and exit.
=item B<-v, --verbose>
Verbose command execution, displaying things like the
commands run, their output, etc.
=item B<-q, --quiet>
Suppress all normal program output; only display errors and
warnings.
=item B<-d, --debug>
Display output to help someone debug this script, not the
process going on.
=back
DESCRIPTION
This module helps you write scripts that conform to best common practices, quickly. Just include the above as a template, and your script
will accept all of the options that are included in the manual page, as well as summarising them when you use the "-h" option.
(Unfortunately, it is not possible to have a `use' dependency automatically add structure to your POD yet, so you have to include the above
manually. If you want your help message and Perldoc to be meaningful, that is.)
Shortcuts are provided to help you abort or die with various error conditions; all of which print the name of the program running (taken
from $0 if not passed). The motive for this is that "small" scripts tend to just get written and forgotten; so, when you have a larger
system that is built out of lots of these pieces it is sometimes guesswork figuring out which script a printed message comes from!
For instance, if your program is called with invalid arguments, you may simply call "abort" with a one-line message saying what the
particular problem was. When the script is run, it will invite the person running the script to try to use the "--help" option, which
gives them a summary and in turn invites them to read the Perldoc. So, it reads well in the source;
@ARGV and abort "unexpected arguments: @ARGV";
$file or abort "no filename supplied";
And in the output;
somescript: no filename supplied!
Try `somescript --help' for a summary of options
On the other hand, if you call "barf", then it is considered to be a hard run-time failure, and the invitation to read the "--help" page to
get usage not given. Also, the messages are much tidier than you get with "die" et al.
open FOO, "<$file" or barf "failed to open $file; $!";
Which will print:
somescript: failed to open somefile; Permission denied
Scriptalicious has no hard dependencies; all the methods, save reading passwords from the user, will work in the absence of extra installed
modules on all versions of Perl from 5.6.0 onwards.
To avoid unnecessary explicit importing of symbols, the following symbols and functions are exported into the caller's namespace:
$VERBOSE
Set to 0 by default, and 1 if "-v" or "--verbose" was found during the call to "getopt()". Extra "-v"'s or "--debug" will push this
variable higher. If "-q" or "--quiet" is specified, this will be less than one.
$PROGNAME
It is recommended that you only ever read this variable, and pass it in via the import. This is not automatically extracted from the
POD for performance reasons.
$CONFIG
Name of the configuration file. Set before a call to "getconf", or read afterwards to see if a config file was used. New in
Scriptalicious 1.16
getopt(@getopt_args)
Fetch arguments via "Getopt::Long::GetOptions". The "bundling" option is enabled by default - which differs from the standard
configuration of Getopt::Long. To alter the configuration, simply call "Getopt::Long::config". See Getopt::Long for more information.
getopt_lenient(@getopt_args)
Just like "getopt()", but doesn't cause a fatal error if there are any unknown options.
getconf(@getopt_args)
Fetches configuration, takes arguments in the same form as getopt()..
The configuration file is expected to be in ~/.PROGNAMErc, /etc/perl/PROGNAME.conf, or /etc/PROGNAME.conf. Only the first found file
is read, and unknown options are ignored for the time being.
The file is expected to be in YAML format, with the top entity being a hash, and the keys of the hash being the same as specifying
options on the command line. Using YAML as a format allows some simplificiations to getopt-style processing - "=s%" and "=s@" style
options are expected to be in a real hash or list format in the config file, and boolean options must be set to "true" or "false" (or
some common equivalents).
Returns the configuration file as Load()'ed by YAML in scalar context, or the argument list it was passed in list context.
For example, this minimal script (missing the documentation, but hey at least it's a start);
getopt getconf
( "something|s" => $foo,
"invertable|I!" => $invertable,
"integer|i=i" => $bar,
"string|s=s" => $cheese,
"list|l=s@" => @list,
"hash|H=s%" => \%hash, );
Will accept the following invocation styles;
foo.pl --help
foo.pl --version
foo.pl --verbose
foo.pl --debug
foo.pl --quiet
foo.pl --something
foo.pl --invertable
foo.pl --no-invertable <=== FORM DIFFERS IN CONFIG FILE
foo.pl --integer=7
foo.pl --string=anything
foo.pl --list one --list two --list three
foo.pl --hash foo=bar --hash baz=cheese
Equivalent config files:
something: 1
invertable: on
invertable: off
integer: 7
string: anything
list:
- one
- two
- three
list: [ one, two, three ]
hash:
foo: bar
baz: cheese
Note that more complex and possibly arcane usages of Getopt::Long features may not work with getconf (patches welcome).
This can be handy for things like database connection strings; all you have to do is make an option for them, and then the user of the
script, or a SysAdmin can set up their own config file for the script to automatically set the options.
getconf_f($filename, @getopt_args)
As getconf(), but specify a filename.
say "something"
Prints a message to standard output, unless quiet mode ("-q" or "--quiet") was specified. For normal program messages.
mutter "progress"
Prints a message to standard output, if verbose mode ("-v") or debug mode ("-d") is enabled (ie, if "$VERBOSE > 0"). For messages
designed to help a user of the script to see more information about what is going on.
whisper "detail"
Prints a message to standard output, if debug mode ("-d") is enabled or multiple verbose options were passed (ie, if "$VERBOSE > 1").
For messages designed to help a person debugging the script to see more information about what is going on internally to the script.
abort "won't go to sea in a storm"
Prints a short program usage message (extracted from the POD synopsis) and exits with an error code.
moan "weather is miserable"
Prints a warning to standard error. It is preceded with the text "warning:". The program does not exit.
protest "don't know the weather report"
Prints an error message to standard error. It is preceded with the text "error:". The program does not exit.
barf "hit an iceberg"
Prints a warning to standard error. It is preceded with the text "warning:". The program does not exit.
run("command", "arg1", "arg2")
Runs a command or closure, barf's with a relevant error message if there is a problem. Program output is suppressed unless running in
verbose mode.
"run()" and the three alternatives listed below may perform arbitrary filehandle redirection before executing the command. This can be
a very convenient way to do shell-like filehandle plumbing.
For example;
run( -in => sub { print "Hello, world!
" },
-out => "/tmp/outfile",
-out2 => "/dev/null",
@command );
This will connect the child process' standard input ("-in") to a closure that is printing ""Hello, world!
"". The output from the
closure will appear on standard input of the run command. Note that the closure is run in a sub-process and so will not be able to set
variables in the calling program.
It will also connect the program's standard output ("-out") to "/tmp/outfile", and its standard error (filehandle 2) to "/dev/null"
(the traditional way of junking error output).
If you wanted to connect two filehandles to the same place, you could pass in "GLOB" references instead;
run( -out => *MYOUT,
-out2 => *MYOUT,
@command );
Any filehandle can be opened in any mode; "-in" merely defaults to meaning "-in0", and "-out" defaults to meaning "-out1". There is no
"-err"; use "-out2". "-rw" exists (defaulting to "-rw0"), but is probably of limited use.
Here is an example of using "prompt_passwd()" to hijack "gpg"'s password grabbing;
my $password = prompt_passwd("Encryption password: ");
my $encrypted = run( -in4 => sub { print "$password
" },
"gpg", "--passphrase-fd", "4", "-c", $file )
run_err("command", "arg2", "arg1")
Same as run, but returns the error code rather than assuming that the command will successfully complete. Again, output it suppressed.
capture("command", "1gra", "2gra")
runs a command, capturing its output, barfs if there is a problem. Returns the output of the command as a list or a scalar.
capture_err("command", "foo")
Works as capture, but the first returned item is the error code of the command ($?) rather than the first line of its output. Also, it
only ever returns the output as a list.
Usage:
my ($rc, @output) = capture_err("somecommand", @args);
hush_exec()
unhush_exec()
"hush_exec" is used to indicate that the programs you are running are only of interest to someone debugging the script. So, the
messages showing commands run and giving execution timings will not be printed without "-vv" (double verbose) or "-d" (debug, which is
the same thing).
start_timer()
show_delta()
show_elapsed()
These three little functions are for printing run times in your scripts. Times are displayed for running external programs with
verbose mode normally, but this will let you display running times for your main program easily.
sci_unit($num, [$unit, $precision])
Returns a number, scaled using normal scientific prefixes (from atto to exa). Optionally specify a precision which is passed to
sprintf() (see "sprintf" in perldoc). The default is three significant figures.
From Scriptalicious 1.08, the "u" character is used in place of the Greek "mu" due to encoding compatibility issues.
time_unit($num, [$precision])
Converts a floating point number of seconds to a human-readable time, the precision specifies the number of significant decimal digits,
which is used to compute a "quanta" for the value given, values below which are not displayed. $precision defaults to 4.
examples:
time_unit(10.1) => "10.10s"
time_unit(1) => "1.000s"
time_unit(0.1) => "100ms"
time_unit(86401,2) => "1d 0h"
time_unit(86401,3) => "1d 0h"
time_unit(86401) => "1d 0h:0m"
time_unit(86400+3600/2) => "1d 0h:30m"
time_unit(86401,5) => "1d 0h:0m:1s"
time_unit(7*86400) => "1w0d 0h"
prompt_regex($prompt, qr/(.*)/)
Prompts for something, using the prompt "$prompt", matching the entered value (sans trailing linefeed) against the passed regex.
Note that this differs from the previous behaviour of prompt_regex, which took a sub.
prompt_sub($prompt, sub { /(.*)/ && $1 })
Prompts for something, using the prompt "$prompt", feeding the sub with the entered value (sans trailing linefeed), to use a default,
the passed sub should simply return it with empty input.
prompt_passwd([$prompt])
Same as "prompt_regex", but turns off echo. $prompt defaults to ""Password: "" for this function.
prompt_string([$prompt])
Prompt for a string.
prompt_int([$prompt])
get an integer
prompt_for([ [$type =] $what])>
Prompts for a value for $what. This constructs a prompt saying, eg ""Enter value for $what"". Calls the equivalent "prompt_foo()"
method.
prompt_yn([$prompt])
prompts for yes or no, presuming neither
prompt_Yn([$prompt])
prompt_yN([$prompt])
prompts for yes or no, presuming yes and no, respectively.
You can also spell these as "prompt_nY" and "prompt_Ny".
anydump($ref)
Dump $ref via "YAML", falling back to "Data::Dumper" if YAML fails to load (or dies during the dump). Returns a string.
tsay($template, $vars)
Prints the template $template with $vars. $template may be included at the end of the file as a data section, for instance:
use Scriptalicious;
tsay hello => { name => "Bernie" };
__END__
__hello__
Hello, [% name %]
[% INCLUDE yomomma %]
__yomomma__
Yo momma's so fat your family portrait has stretchmarks.
This will print:
Hello, Bernie
Yo momma's so fat your family portrait has stretchmarks.
Note that the script goes to lengths to make sure that the information is always printed whether or not Template Toolkit is installed.
This gets pretty verbose, but at least solves the "argh! that script failed, but I don't know why because it needed this huge
dependency to tell me" problem.
For example, the above would be printed as:
scriptname:
foo()
If you've got a short little Perl function that implements something useful for people writing Shell scripts in Perl, then please feel
free to contribute it. And if it really is scriptalicious, you can bet your momma on it getting into this module!
SEE ALSO
Simon Cozen's Getopt::Auto module does a very similar thing to this module, in a quite different way. However, it is missing "say", "run",
etc. So you'll need to use some other module for those. But it does have some other features you might like and is probably engineered
better.
There's a template script at "Documentation and help texts" in Getopt::Long that contains a script template that demonstrates what is
necessary to get the basic man page / usage things working with the traditional Getopt::Long and Pod::Usage combination.
Getopt::Plus is a swiss army chainsaw of Getopt::* style modules, contrasting to this module's approach of elegant simplicity (quiet in the
cheap seats!).
Getopt::EUCLID is Damian Conway's take on this.
Finally, if you don't mind the dependencies of Moose (or Mouse), then MooseX::Getopt and MooseX::SimpleConfig are much more elegant
approaches to getopt handling and configuration than this module.
If you have solved this problem in a new and interesting way, or even rehashed it in an old, boring and inelegant way and want your module
to be listed here, please contact the
AUTHOR AND LICENSE
Sam Vilain, samv@cpan.org
Copyright 2005-2008, Sam Vilain. All rights reserved. This program is free software; you can use it and/or distribute it under the same
terms as Perl itself; either the latest stable release of Perl when the module was written, or any subsequent stable release.
Please note that this applies retrospectively to all Scriptalicious releases; apologies for the lack of an explicit license.
perl v5.10.1 2010-05-03 Scriptalicious(3pm)