Updating the path Variable

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Launching Perl from the Command Line

You can use any legal filename for a Perl script, but by convention Perl scripts have the suffix '.pl.' Suppose you want to run the Perl script called abc.pl. After you have updated your PATH variable in a shell on your machine, you can run script abc.pl as follows:

perl -w abc.pl

The '-w' switch is extremely useful and will provide valuable information, such as variables that have been invoked only once. This type of information often indicates that you mistyped a variable name. Perl has a number of command-line options, and you can see the entire list by typing the following at the command line:

perl -h

The preceding command will display something similar to the following output:

Usage: C:\bin\perl.exe [switches] [--] [programfile] [arguments]   -0[octal]       specify record separator (\0, if no argument)   -a              autosplit mode with -n or -p (splits $_ into @F)   -C              enable native wide character system interfaces   -c              check syntax only (runs BEGIN and CHECK blocks)   -d[:debugger]   run program under debugger   -D[number/list] set debugging flags (argument is a bit mask or 
     alphabets)   -e 'command'    one line of program (several -e's allowed, omit 
     programfile)   -F/pattern/     split() pattern for -a switch (//'s are 
     optional)   -i[extension]   edit <> files in place (makes backup if 
     extension supplied)   -Idirectory     specify @INC/#include directory (several -I's 
     allowed)   -l[octal]       enable line ending processing, specifies line 
     terminator   -[mM][-]module  execute `use/no module...' before executing 
     program   -n              assume 'while (<>) { ... }' loop around program   -p              assume loop like -n but print line also, like 
     sed   -P              run program through C preprocessor before 
     compilation   -s              enable rudimentary parsing for switches after 
     programfile   -S              look for programfile using PATH environment 
     variable   -T              enable tainting checks   -u              dump core after parsing program   -U              allow unsafe operations   -v              print version, subversion (includes VERY 
     IMPORTANT perl info)   -V[:variable]   print configuration summary (or a single 
     Config.pm variable)   -w              enable many useful warnings (RECOMMENDED)   -W              enable all warnings   -X              disable all warnings   -x[directory]   strip off text before #!perl line and perhaps cd 
     to directory

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