Perl in the Command Line

-c: Test Compiling -c : causes Perl to check the syntax of the program and then exit without executing it. It will execute BEGIN , UNITCHECK , CHECK , and use blocks, because these are considered as occurring outside the execution of your program. It will not execute INIT and END blocks.

-c : causes Perl to check the syntax of the program and then exit without executing it.

It will execute BEGIN , UNITCHECK , CHECK , and use blocks, because these are considered as occurring outside the execution of your program.

It will not execute INIT and END blocks.

-w, -W and -X: Warnings -w : This turns on warnings that Perl will then give you if it finds any of a number of problems in your code. The -w option has been replaced by the use warnings pragma. -W: Enables all warnings regardless of no warnings or $^W . -X: Disables all warnings regardless of use warnings or $^W . $> perldoc perllexwarn

-w : This turns on warnings that Perl will then give you if it finds any of a number of problems in your code. The -w option has been replaced by the use warnings pragma.

-W: Enables all warnings regardless of no warnings or $^W .

-X: Disables all warnings regardless of use warnings or $^W .

$> perldoc perllexwarn

-d: Debugging -d : This option puts you into the Perl debugger. -d:DProf : executes the program using the Devel::DProf profiler, combined with dprofpp may help you to find where is your program slow. $> perldoc perldebtut $> perldoc perldebug

-d : This option puts you into the Perl debugger.

-d:DProf : executes the program using the Devel::DProf profiler, combined with dprofpp may help you to find where is your program slow.

$> perldoc perldebtut $> perldoc perldebug

-e: eval -e: allows you to define code to be executed by the compiler. $> perl -e 'print "Hello World"' "Hello World" program in the shell. -E : like -e, but enables all optional features

-e: allows you to define code to be executed by the compiler.

$> perl -e 'print "Hello World"' "Hello World" program in the shell.

-E : like -e, but enables all optional features

-M: module Import -M : This option imports a module. -Mmodule is the same has use module . $> perl –Mdiagnostics script.pl Get better error message. perl -MLWP::Simple -e 'print get($ARGV[0]), "
"' http://perl.com Better as an alias.

-M : This option imports a module. -Mmodule is the same has use module .

$> perl –Mdiagnostics script.pl Get better error message.

perl -MLWP::Simple -e 'print get($ARGV[0]), "
"' http://perl.com Better as an alias.

-n: Looping -n : Perl assumes the following loop around your program: LINE: while (<>) { # Your code }

-n : Perl assumes the following loop around your program: LINE: while (<>) { # Your code }

-n: Looping The command $> perl -ne 'print &quot;$. - $_&quot;' in.txt Would become LINE: while (<>) { print &quot;$. - $_&quot; } This code prints each line of the file together with the current line number.

The command $> perl -ne 'print &quot;$. - $_&quot;' in.txt Would become LINE: while (<>) { print &quot;$. - $_&quot; } This code prints each line of the file together with the current line number.

-p: Looping with print -p : Perl assumes the following loop around your program: LINE: while (<>) { # your code goes here } continue { print or die &quot;-p destination: $!
&quot;; } This uses a continue block on a while loop to ensure that the print statement is always called.

-p : Perl assumes the following loop around your program: LINE: while (<>) { # your code goes here } continue { print or die &quot;-p destination: $!
&quot;; } This uses a continue block on a while loop to ensure that the print statement is always called.

-p: Looping with print The -n example $> perl -ne 's/PHP/Perl/g; print' in.txt or the simpler $> perl -pe ' s/PHP/Perl/g ' in.txt It's very common to see command line programs that use Unix I/O redirection like this: $> perl -pe 's/PHP/Perl/g' in.txt > out.txt

The -n example $> perl -ne 's/PHP/Perl/g; print' in.txt

or the simpler $> perl -pe ' s/PHP/Perl/g ' in.txt

It's very common to see command line programs that use Unix I/O redirection like this: $> perl -pe 's/PHP/Perl/g' in.txt > out.txt

-i: edit in place $> perl -i -pe 's/PHP/Perl/g' in.txt Substitute every PHP occurence by Perl -i[extension] : edit in place. Case extension exists the original file is renamed, otherwise the file is overwitten. If the extension doesn't contain a * , then it is appended to the end of the current filename. If the extension does contain one or more * characters, then each * is replaced with the current filename.

$> perl -i -pe 's/PHP/Perl/g' in.txt Substitute every PHP occurence by Perl

-i[extension] : edit in place. Case extension exists the original file is renamed, otherwise the file is overwitten.

If the extension doesn't contain a * , then it is appended to the end of the current filename. If the extension does contain one or more * characters, then each * is replaced with the current filename.

-l: Line-ending processing -l[octnum] : Automatic line-ending processing. It assigns $ to have the value of octnum . Without octnum, $ will be assigned to $/ . After chomp() everything on input Adds $ (the output record separator) to each print

-l[octnum] : Automatic line-ending processing.

It assigns $ to have the value of octnum . Without octnum, $ will be assigned to $/ .

After

chomp() everything on input

Adds $ (the output record separator) to each print

-a and -F: Autosplitting -a: Splits the $_ whith a space while (<>) { @F = split(' '); # your code } -F: choses a diferent separator perl -F, -ane 'print join &quot; &quot;, @F' data.csv converts a csv into a tsv. Not really true but enough for example propose.

-a: Splits the $_ whith a space while (<>) { @F = split(' '); # your code }

-F: choses a diferent separator

perl -F, -ane 'print join &quot; &quot;, @F' data.csv converts a csv into a tsv. Not really true but enough for example propose.

$> perldoc perlrun

$> perldoc perlrun

Q&A