Perl
Reading
http://www.perl.org/books/beginning-perl/
Perl
Pathologically Eclectic Rubbish Lister
variables
the three types of variables in Perl are:
scalars = numbers, strings, or references denoted $ arrays = sequentially-numbered lists of scalars denoted @ hashes.= key-referenced lists of scalars denoted %
operators
Operator Num Str -------------------------------------- Equal == eq Not equal != ne Less than < lt Greater than > gt Less than or equal to <= le Greater than or equal to >= ge
man pages
perl - overview perlfaq - frequently asked questions perltoc - doc TOC perldata - data structures perlsyn - syntax perlop - operators and precedence perlrun - execution perlfunc - builtin functions perltrap - traps for the unwary perlstyle - style guide "perldoc" and "perldoc -f"
cpan
Comprehensive perl archive network
Perl kurs
Christer Ekholm First two letters and first letter of last name@init.se TIMTOWTDI (There Is More Than One Way To Do It)
Dictionary
regexp regular expression . a* a? ^a a$,perls RE för andra. semantik meaning that is expressed in a language and words notation ways to represent a mathematical equation analogi motsvarighet, nagot svart beskrivs enkelt iteration upprepning deklarera förklara definera definera subrutiner context sammanhang explicit uttryckligen implicit underförstått logiska operatorer and,or,not,||,&&,! aritmetisk +-/* bitoperatorer AND,OR,XOR,leftand right shift. re reguljära utryck, mönsterpassning.
relation operatorer
numeriska sträng == != eq ne < > lt gt <= >= le ge jämförelse operatörer
numeriska sträng
<=> cmp citatecken "" variabler expanderar qq, variabler oförändrade q, `` exekveras qx
How to get information
perldoc -f variabler Show help page for variables perldoc -f -X Show file handle test. perldoc perlform Format information perldoc Getopt::Long Show help for Getopt perldoc -q Letar i perl faq perldoc perlmodlib Lista inbyggda moduler perldoc perlpod
Debug
emacs M-x perldb Debugga perl i emacs perl -d:ptkdb /scrpt Debugga perl
Perl code
use strict; explesist namnge package variable use warning; show warning messages perl -w show warning messages use Getopt::Long: Use getoptions module
package mypkg; change package
Perl Oneliners:
perl -ne 'print if /a/' Grep all lines containing a. (-n create a loop) (-e, allows you to define Perl code to be executed by the compiler)
perl -e 'print join("\n",@INC),"\n"' Var söker perl efter moduler
perl -c kod.pl Kontrollera koden.
regex
. one key
^ beginning of line
$ end of line
/^[xfi]/ Starting with one x or f or i
/^[h-j]/ Starting with one h or i or j
() Deluttryck
quantifier how much a string matches.
? Noll eller en gång
a* a with 0 to unlimit a
a+ one or more a
{m} exackt m ggr
{m,} minst m ggr
{m,n} minst m max n ggr
=~ m|^abc| matchar abc i början
.+? matchar så lite som möjligt
modifierare
/i/i matchar i case insensitiv
a.b a any key b
^a.c$ starting with a any key end with c
X1* X1 folles by 0 to many 1
^[]abc] strings starting with any of ]abc
[^zxy] Does not have any of zxy in possition
a{8} aaaaaaaa
uttr{m,n} uttr förekommer mellan m och n gånger
^ *$ empty line or only blanks
Special meaning
$ skalär
@ lista
% hash, associativa vektorer
$# maximun index in list
$@ string that eval generates.
\s remove space,tab,lf...
\s+ godtyckligt
\l Convert to lower case.
$_ Default output input
$$ processid
$? exit status
@_ variable to send to subroutin
@ARGV argument list. ('-v','-g','10','logfile')
$|=1; dont flush output stty
$"=','; dubbelfnuttade listor
_ fil operatorer och stat kan återänväda stat förfrågan.
$. Radräknare
$1 Delutryck som matchade
local $/
@INC directories to find per modules, add directory export PERL5LIB=/bin:/hej
&sub subrutin
$var2=\$var refere var2 to var
@list('a',1,$a) add tree elements to list
@list([@odd]) add copy of list called anonymous list
$list[5] 6 possition in list
@list = qw<Jan Feb>; Generate list
$hash{'var'} element with index var in hash
%hash{'a'}='5'; add key a value 5
if (exist($hash{a})){ run if key a exist i hash hash
delete($hash{'a'}); delete key a fron hash
split(' ',$str); split list output whith ' '
my lexikal variabel, lokal variabel $main::var main variabel
styrstrukturer
- iterationer
while [EXPR] BLOCK until [EXPR] BLOCK do BLOCK while [EXPR] do BLOCK until [EXPR] for VAR (EXPR) BLOCK for (EXPR1; EXPR2; EXPR3) BLOCK
- selection
if (EXPR) BLOCK if (EXPR) BLOCK1 elsif (EXPR2) BLOCK2... elxe BLOCKn unless (EXPR) BLOCK
filehandels
STDIN,STDOUT,STDERR
sträng list konverteringar
join (EXPR,LIST)
@words = ("merry", "go", "round");
$str = join("-",@words);
split (REGEXP,EXPR)
$str = "sys:x:3:3:sys:/dev:/bin/sh";
@fields = split (/:/, $str);
for $rad ( @fields ){
print "$rad\n";
}
sub usage {
print "use this command with optional -v"
}
&subrutin(15,101,38) arguments are sent to a subroutin as a list
-command options.
use Getopt::Long;
my %opts;
GetOptions(\%opts,'v','g=i') || &usage;
print "$opts{g}\n";
sub usage {
print STDERR "Usage: option.pl [-v][-g n]";
exit 1;
}
-globala symboltabellen
foreach my $var ( keys %main::){
print "$var\n";
formatting.
my $rand1 = int(rand (90));
my $rand2 = int(rand (10));
my $rand3 = int(rand (50));
printf ("%6d %6d %6d\n",$rand1,$rand2,$rand3);
filehandlers
print "Who are you?\n"; my $name = <STDIN>; chomp($name); print "You are $name!!!\n";
print contents of file.
my $file = "/tmp/test";
open(IN,'<',$file) || die "open $file failed: $!";
# Loopa på rader i infilen.
while ( <IN> ) {
print $_;
}
diamond operator @ARGV
#!/usr/bin/perl
while (<>){
print;
}
list files
opendir(DIR,"/etc"); my @files = sort grep(/x/,readdir(DIR)); closedir(DIR);
user external program
open(PING,'-|','/bin/ping -c 3 pizza');
while (defined(my $ping = <PING>)){
print "$ping";
}
close PROG;
Backslash magic
\t tab (HT, TAB) \n newline (LF, NL) \r return (CR) \f form feed (FF) \a alarm (bell) (BEL) \e escape (think troff) (ESC) \033 octal char (think of a PDP-11) \x1B hex char \c[ control char \l lowercase next char (think vi) \u uppercase next char (think vi) \L lowercase till \E (think vi) \U uppercase till \E (think vi) \E end case modification (think vi) \Q quote (disable) pattern metacharacters till \E \w Match a "word" character (alphanumeric plus "_") \W Match a non-word character \s Match a whitespace character \S Match a non-whitespace character \d Match a digit character \D Match a non-digit character