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Top Forums Shell Programming and Scripting Interpreting arguments in Perl program. Post 302716451 by D2K on Tuesday 16th of October 2012 11:49:25 AM
Old 10-16-2012
Interpreting arguments in Perl program.

Hello.
I'm new to Perl and I am not sure how to interpret command line arguments in the program. I am writing a program similar to the Unix utility 'tail' and need to check if first argument is '-1' ([dash]1) or any arbitrary number of lines to output. How would I write an 'if' statement to check for the dash (-) and a number? Checking for the dash is trivial below.
Code:
if ($ARGV[0] eq "-")
{
    print "I think it works\n";
}

How can I parse the dash with a number attached? Any numerical value?

Sample program run below:

File 'samp.txt' contains:
Hello World
This
Is
A
Test

-------
$tail.pl -3 samp.txt
Is
A
Test
 

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dos2unix(1)						      General Commands Manual						       dos2unix(1)

NAME
dos2unix - DOS/MAC to UNIX text file format converter SYNOPSYS
dos2unix [options] [-c convmode] [-o file ...] [-n infile outfile ...] Options: [-hkqV] [--help] [--keepdate] [--quiet] [--version] DESCRIPTION
This manual page documents dos2unix, the program that converts plain text files in DOS/MAC format to UNIX format. OPTIONS
The following options are available: -h --help Print online help. -k --keepdate Keep the date stamp of output file same as input file. -q --quiet Quiet mode. Suppress all warning and messages. -V --version Prints version information. -c --convmode convmode Sets conversion mode. Simulates dos2unix under SunOS. -o --oldfile file ... Old file mode. Convert the file and write output to it. The program default to run in this mode. Wildcard names may be used. -n --newfile infile outfile ... New file mode. Convert the infile and write output to outfile. File names must be given in pairs and wildcard names should NOT be used or you WILL lost your files. EXAMPLES
Get input from stdin and write output to stdout. dos2unix Convert and replace a.txt. Convert and replace b.txt. dos2unix a.txt b.txt dos2unix -o a.txt b.txt Convert and replace a.txt in ASCII conversion mode. Convert and replace b.txt in ISO conversion mode. Convert c.txt from Mac to Unix ascii format. dos2unix a.txt -c iso b.txt dos2unix -c ascii a.txt -c iso b.txt dos2unix -c mac a.txt b.txt Convert and replace a.txt while keeping original date stamp. dos2unix -k a.txt dos2unix -k -o a.txt Convert a.txt and write to e.txt. dos2unix -n a.txt e.txt Convert a.txt and write to e.txt, keep date stamp of e.txt same as a.txt. dos2unix -k -n a.txt e.txt Convert and replace a.txt. Convert b.txt and write to e.txt. dos2unix a.txt -n b.txt e.txt dos2unix -o a.txt -n b.txt e.txt Convert c.txt and write to e.txt. Convert and replace a.txt. Convert and replace b.txt. Convert d.txt and write to f.txt. dos2unix -n c.txt e.txt -o a.txt b.txt -n d.txt f.txt DIAGNOSTICS
BUGS
The program does not work properly under MSDOS in stdio processing mode. If you know why is that so, please tell me. AUTHORS
Benjamin Lin - <blin@socs.uts.edu.au> Bernd Johannes Wuebben (mac2unix mode) <wuebben@kde.org> MISCELLANY
Tested environment: Linux 1.2.0 with GNU C 2.5.8 SunOS 4.1.3 with GNU C 2.6.3 MS-DOS 6.20 with Borland C++ 4.02 Suggestions and bug reports are welcome. SEE ALSO
unix2dos(1) mac2unix(1) 1995.03.31 dos2unix v3.0 dos2unix(1)
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