Lodbrok.be
find modules using @INC
$ find `perl -le 'print for grep {$_ ne q{.}and -d} @INC'` -name "*.pm"
or
$ find `perl -e 'print "@INC"'` -name '*.pm' -print
perl -MCPAN -e shell
cpan[2]> o conf init /proxy/
Your ftp_proxy? [a.b.c.d] ftp://server:21
Your http_proxy? [a.b.c.d] http://server:8080
Your no_proxy? [] <== if left empty it will ask for username and password!!
cpan[3]> reload index # to test connection
cpan[3]> o conf commit
get modules from CPAN
$ perl -MCPAN -eshell
> m /FTP/
> o conf [init]
...
> o conf commit
# or use export http_proxy instead.
> o conf http_proxy ''
> o conf commit
check if module is installed (read: available)
$ perl -M<some::module> -e '1'
Tip: eat your daily "pie"
-p loop -i inplace_edit[with_backup] -e code perl -p -i[.backup-extension] -e 's#old_string#new_string#ig' file(s)
Tip: "lane" will do it for you
-l strips newlines on input, and adds them on output. -a enables auto-split of input into the @F array. -n loops over and does not print input. -e specifies Perl expressions. -F specifies the characters to split on with the -a option (default = spaces). -p loops over and prints input. $ perl -F: -lane 'print $F[0]' /etc/passwd $ perl -F: -lape '$_ = $F[0]' /etc/passwd
Tip: For nice regex, use /x
#!/usr/bin/perl $x="aaa:bbbb:ccc-ddd"; $x =~ m/ (.+?) # non greedey tot eerste dubbel punt :(.+) # blah, blah, blah -(.+) # the rest /x; print "_ $1 _ $2 _ $3 _ \n";
Converting text files between : Mac OS - UNIX - Windows
EOL termination
Windows to Unix
$ perl -p -e 's/\r$//' < winfile.txt > unixfile.txt
Unix to Windows
$ perl -p -e 's/\n/\r\n/' < unixfile.txt > winfile.txt
$ perl -p -i -e 's/([^\r])\n/$1\r\n/' somefile.txt
Mac to Unix
$ perl -p -e 's/\r/\n/g' < macfile.txt > unixfile.txt
Unix to Mac
$ perl -p -e 's/\n/\r/g' < unixfile.txt > macfile.txt
Reverse a entire text file (better then tail -r)
perl -e 'print reverse <>'
# Find the position of a string
grep %% f1 | perl -lne '$x=index($_,"%%");print $x;'
# insert "New" after column "2"
cat f1 | perl -pe 's/((?:\d\s){2})(.*)/$1New $2/'
# insert "New" at position 20
cat f1 | perl -pe 'substr($_,20,0) = "New"'
Perl uses the -0 option to allow changing the input record separator. Use -00 to operate in paragraph mode, and -0777 to treat the file as a single line. The paragraphs file contains the -0 documentation from perlrun, used in the following example:
$ perl -00 -ne 'print if /special/' paragraphs The special value 00 will cause Perl to slurp files in paragraph mode. The value 0777 will cause Perl to slurp files whole because there is no legal byte with that value.
Parsing the entire input file as a single line can be used to alter the newlines that otherwise require a range operator to deal with, as shown above. By treating an entire file as a single line, a s///g expression can eliminate runs of blank lines:
$ cat input foo bar $ perl -0777 -pe 's/\n+/\n/g' input foo bar
stringtoinsert=$1
rm -f f1
vi f1
position=$(grep %% f1 | perl -lne '$x=index($_,"%%");print $x;')
cat f1 | perl -pe 'substr($_,'$position',0)="'"${stringtoinsert}"'";' | grep -v "%%"
rm f1
todo: write completely in Perl; cat file into new script; add feature to delete columns
Where does Perl load modules from in its use and require statements? It loads them from directorys in a special list called @INC, from files with a .pm extension in those directorys. When Perl's installed, @INC is set to a list of directorys that includes generic locations for its standard modules, some release specific directories, and "." the current directory, which are checked in order each time you do a use or require.
Some ways to modify @INC
==> You can add to the list in @INC by using the -I command line option:
perl -I /Users/grahamellis/jan06 i2
says "run the perl program i2, additionally checking the jan06 directory for modules"
==> You can add to the list within your program by doing so in a BEGIN block prior to the use statements:
BEGIN {
push @INC,"/Users/grahamellis/jan06";
}
use demo;
print "hello world";
Rather curiously, use calls are run at compile time not at run time ... but then so are BEGIN blocks ... so you put your manipulation of @INC into one of those to get it to happen early enough.
==> You can add to the beginning of the list by setting the PERL5LIB environment variable prior to running your program:
export PERL5LIB=/Users/grahamellis/jan06
and you can use a colon separated list for that if you
==> edit the perl binary but this is a dirty hach that does not allow you to add bytes (paths)
==> re-compile perl after "make distclean" but that implies you already compiled Perl yourself before.
TODO