Dpuiu Perl
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Style
- Style
- perltidy
POD
- POD; pod2html pod2latex pod2man pod2text pod2usage
- make sure to leave 1 empty line before/after cut
Example:
$ cat test.pl
=pod
=head1 sub max(number,number)
Returns max of 2 numbers
=cut
sub max
{
my ($a,$b)=@_;
return ($a>$b)?$a:$b;
}
=head1 sub min(number,number)
Returns min of 2 numbers
=cut
sub min
{
my ($a,$b)=@_;
return ($a<$b)?$a:$b;
}
print max(1,2),"\n";
print min(1,2),"\n";
$ perdoc test.pl sub max(number,number) Returns max of 2 numbers sub min(number,number) Returns min of 2 numbers
Functions
Map
sub addString { return @_[0].$_[1]; }
@myNames = ('jacob', 'alexander', 'ethan', 'andrew');
@ucNames = map(addString($_,"."), @myNames);
@a = (1,3,5);
In place editing
- Edit a file in place: -i
perl -i.bck script.pl xxx => xxx(new), xxx.bck(old)
- dos2unix
perl -i -pe 's/\r//g' file
- unix2dos
perl -i -pe 's/\n/\r\n/' file
Cmd line options
- BEGIN/END blocks
perl -ane 'BEGIN { print "sum\n"} END { print $sum,"\n" } $sum += $F[0]; '
- Check all files
ls *pl | perl -pe 'print "perl -c "; '
Regular Expressions
- Maximal match (default)
echo $PERLLIB | perl -ane '/^(.+):/; print $1,"\n"'
- Minimal match
echo $PERLLIB | perl -ane '/^(.+?):/; print $1,"\n"' /fs/sz-user-supported/Linux-x86_64/lib
- Translation:
$_ =~ tr/abc/ABC/
- All matches
while($text=~m/($pattern)/g) { print "$` $& $'\n"; }
Search directories
- -Idir : same as "use lib dir_name"
default: /usr/include & /usr/lib/perl add dirs to PERLLIB env variable <=> @INC perl -e '$,="\n"; print @INC ; '
- Find installed modules
perl -e 'foreach(@INC) { if(-d $_) {system "find $_ -type d -name Bio\n";}} '
perl -e 'foreach(@INC) { if(-f $_) {system "find $_ -type f -name SeqIO.pm\n";}} '
perl -e 'foreach(@INC) { if(-d $_) {system "find $_ -type f -path Bio/SeqIO.pm\n";}} ' # not working though it should!
~/bin/findPerlModule.pl Bio::SeqIO
Command line arguments
- PERL5OPT : -[DIMUdmtw] switches
Debug
- caller function : shows the context
print STDERR "DEBUG: context: ",(caller(0))[3],"\n";
sub myDie { print STDERR "DEBUG: context: ",(caller(1))[3],"\n"; }
sub b { myDie(); }
- Example
use Data::Dumper; ... Dumper(\@list); Dumper(\%hash);
- perldebug
! : re-exectutes prev command !<n> : re-exectutes command <n> H : show command history save debug.history : saves debug history source debug.history : runs debug history
Serialization
- Writes object to a file
- Example
$ cat dump.pl use Data::Dumper; require "delta.pm"; my $result=delta2result(); print Data::Dumper->Dump([$result],['result']);
$cat eval.pl use Data::Dumper; require "delta.pm"; undef $/; eval <>; print Data::Dumper->Dump([$result],['result']);
Redefine commands
- Example:
use subs 'cmp';
Libraries
- prefix.pm
... 1;
- prefix.pl
require "prefix.pm": ...
Modules
- -M moldule: same as "use module_name"
perl -MLWP::Simple -e' print head "http://www.example.com"' perl -e 'use LWP::Simple; print head "http://www.example.com"'
- Installation(Makefile)
$ perl Makefile.PL PREFIX=~/szdevel/CPAN $ make $ make test $ make install $ find ~/szdevel/CPAN -type f bin/xmltidy lib/perl5/site_perl/5.8.5/XML/Tidy.pm lib64/perl5/site_perl/5.8.5/x86_64-linux-thread-multi/auto/XML/Tidy/.packlist lib64/perl5/5.8.5/x86_64-linux-thread-multi/perllocal.pod share/man/man3/XML::Tidy.3pm
- Installation(Build)
$ perl Build.PL --prefix ~/szdevel/CPAN $ ./Build test $ ./Build install
Useful ones:
- Getopt::Long
- File::Find
Variables
- spec_variables
- $0 : program name
- $. : input line number
- $, : output field separator (default="")
$ perl -e '$, = "\n";print (1,2,3,"");' 1 2 3
$ perl -e '$, = " "; @l=("a","b","c"); print map {uc($_)} @l; '
A B C
- $/ : the input record separators (default="\n")
- $\ : output record separators (default="")
Argument passing
Example:
sub test
{
my ($options)=@_;
my %options=%{$options};
print $options{a},"\n";
}
my %options;
$options{a}="a";
test(\%options);
Files
- open(IN, '-') # Open standard input
- open(IN, '>-') # Open standard output
- @lines = <IN> # read all lines in the file
- $line = <IN> # read one line
Hashes
- foreach $person (keys %ages) {}
- foreach $age (values %ages) { }
- while (($person, $age) = each(%ages)) {}
- cmd hash
my %cmd_hash = (scarf2std=>\&scarf2std, fqint2std=>\&fqint2std);
&{$cmd_hash{$cmd}};
sub scarf2std {...}
sub fqint2std {...}
Security
File names
- use open(IN,"<" ,filename) instead of open(IN,filename)
filename could be "rm -fr * |"
- check file names for illegal characters
$filename =~ /^([\w.-]+)$/)
Taint mode
#!/usr/bin/perl -wT
use strict;
delete @ENV{qw(IFS CDPATH ENV BASH_ENV)};
$ENV{PATH} = "/usr/bin/:/usr/local/bin";
Profiling
perl -d:DProf test.pl => tmon.out dprofpp
CPAN
- FAQ
- Check if a module is installed
perl -MModule -e 1 perl -MXML::Merge -e 1
- Edit CPAN configuration
~/.cpan/CPAN/MyConfig.pm
'makepl_arg' => q[LIB=~/szdevel/CPAN/lib \
INSTALLBIN=~/szdevel/CPAN/bin \
INSTALLSCRIPT=~/szdevel/CPAN/bin \
INSTALLMAN1DIR=~/szdevel/CPAN/share/man/man1/
INSTALLMAN3DIR=~/szdevel/CPAN/share/man/man3/],