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perl command line options

 

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Here is a list of switches that you can pass to the perl interpreter:

-0
    Lets you specify the record separator ($/) as an octal number.
    For example, -0055 will cause records to end on a dash. If no 
    number is specified, records will end on null characters. The special 
    value of 00 will place Perl into paragraph mode. And 0777 will force 
    Perl to read the whole file in one shot because 0777 is not a legal 
    character value. 

-a
    This option must be used in conjunction with either the -n or 
    -p option. Using the -a option will automatically feed input lines
    to the split function. The results of the split are placed into
    the @F variable.

-c
    This option lets you check the syntax of your script without
    fully executing it. The BEGIN blocks and use statements are still
    executed because they are needed by the compilation process.

-d
    This option lets you start the Perl debugger.

-D
    This option lets you turn on different behaviors related to
    the debugging process. The following table shows you the sub-options
    that can be used. Please note, however, that not all releases of Perl
    can use this feature. For example, the hip port of Perl for Win32 can't.
    If your version of Perl does not have this option, you will see the
    message "Recompile perl with -DDEBUGGING to use -D switch" when you try
    it. If you want to watch your script as it executes, use -D14. Following
    is a list of the other values that you can use. You can add the numbers
    together to specify more than one behavior (such as 8+4+2 = 14) or
    you can use the letters.

    1 		p 	Tokenizing and Parsing
    2 		s 	Stack Snapshots
    4 		l 	Label Stack Processing
    8 		t 	Trace Execution
    16 		o 	Operator Node Construction
    32 		c 	String/Numeric Conversions
    64 		P 	Print Preprocessor Command for -P
    128 	m 	Memory Allocation
    256 	f 	Format Processing
    512 	r 	Regular Expression Parsing
    1024 	x 	Syntax Tree Dump
    2048 	u 	Tainting Checks
    4096 	L 	Memory Leaks (not supported any more)
    8192 	H 	Hash Dump - usurps values()
    16384 	X 	Scratchpad Allocation
    32768 	D 	Cleaning Up

-e
    The option lets you specify a single line of code on the command
    line. This line of code will be executed in lieu of a script file.
    You can use multiple -e options to create a multiple line program-
    although given the probability of a typing mistake, I'd create a
    script file instead. Semi-colons must be used to end Perl statements
    just like a normal script.

-F
    This option modifies the behavior of the -a option. It lets you
    change the regular expression that is used to split the input lines.
    For example, -F /:+/ will split the input line whenever one or more
    colons are found. The slashes are optional; they simply delimit the 
    pattern if they are there. I use them for their aesthetic value.

-I
    This option lets you edit files in-place. It is used in conjunction 
    with the -n or -p option. See "Example: Using the -i option" for more 
    information.

-I
    This option is used in conjunction with the -P option. It tells 
    the C preprocessor where to look for include files. The default search 
    directories include /usr/include and /usr/lib/Perl.

-l
    This option turns on line-ending processing. It can be used to set 
    the output line terminator variable ($/) by specifying an octal value.

-n
    This option places a loop around your script. It will automatically
    read a line from the diamond operator and then execute the script. It 
    is most often used with the -e option.

-p
    This option places a loop around your script. It will automatically 
    read a line from the diamond operator, execute the script, and then 
    print $_. It is most often used with the -e option.

-P
    This option will invoke the C preprocessor before compiling your 
    script. This might be useful if you have some C programming experience 
    and would like to use the #include and #define facility. The C 
    preprocessor can also be used for conditional compilation. Use the -I 
    option to tell Perl where to find include files.

-s
    This option lets you define custom switches for your script.

-S
    This option makes Perl search for the script file using the PATH 
    environment variable. It's mostly used with UNIX systems that don't
    support the #! Line. The docs/perlrun.htm documentation file that 
    comes with your Perl distribution has more information about this 
    option.

-T
    This UNIX-based option turns on taint checking. Normally, these 
    checks are only done when running setuid or setgid.

-U
    This UNIX-based option will let Perl do unsafe operations. 

-v
    This option will display the version and patchlevel of your 
    Perl executable.

-w
    This option prints warnings about unsafe programming practices.
    Newer versions of Perl (since 5.6.0) offer the pragma 'use warnings'
    and 'no warnings' which is more flexible than the command-line option.
    The use of -w is discouraged for new developments. 

-x
    This option will let you extract a Perl script from the middle of
    a file. This feature comes in handy when someone has sent you a script 
    via e-mail. Perl will scan the input file looking for a #! line that 
    contains the word perl. When it is found, it will execute the script 
    until the __END__ token is found. If a directory name is specified 
    after the -x option, Perl will switch to that 
    directory before executing the script. 

Comments:

2008-11-03, 15:49:19
anonymous from Croatia/Hrvatska  
rating
thanks man, that was simple and very useful !

 

 

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