Request for a FAQ 
Author Message
 Request for a FAQ

        Do you kmow whether there is a FAQ for perl ? If so, do you know how
one could get it ?


Sat, 02 Apr 1994 06:28:09 GMT  
 Request for a FAQ

:       Do you kmow whether there is a FAQ for perl ? If so, do you know how
:one could get it ?

It really shouldn't have expired yet, but apparently it has.  I put a
long expire last time, which is good, as I just returned from 3
weeks away from the office.  I'll post it again.


Sat, 02 Apr 1994 10:30:31 GMT  
 Request for a FAQ
(No appreciable diffs this time. --tchrist)

[Last changed: $Date: 91/09/13 15:51:30 $ by $Author: tchrist $]

This article contains answers to some of the most frequently asked questions
in comp.lang.perl.  They're all good questions, but they come up often enough
that substantial net bandwidth can be saved by looking here first before
asking.  Before posting a question, you really should consult the Perl man
page; there's a lot of information packed in there.

Some questions in this group aren't really about Perl, but rather about
system-specific issues.  You might also consult the Most Frequently Asked
Questions list in comp.unix.questions for answers to this type of question.

This list is maintained by Tom Christiansen.  If you have any suggested
additions or corrections to this article, please send them to him at either

initially reviewing this list for accuracy and especially for writing and
releasing Perl in the first place.

List of Questions:

    1)   What is Perl?
    2)   Where can I get Perl?
    3)   How can I get Perl via UUCP?
    4)   Where can I get more documentation and examples for Perl?
    5)   Are archives of comp.lang.perl available?
    6)   How do I get Perl to run on machine FOO?

    8)   Why don't backticks work as they do in shells?  
    9)   How come Perl operators have different precedence than C operators?
    10)  How come my converted awk/sed/sh script runs more slowly in Perl?
    11)  There's an a2p and an s2p; why isn't there a p2c?
    12)  Where can I get undump for my machine?
    13)  How can I call my system's unique C functions from Perl?
    14)  Where do I get the include files to do ioctl() or syscall()?
    15)  Why doesn't "local($foo) = <FILE>;" work right?
    16)  How can I detect keyboard input without reading it?
    17)  How can I make an array of arrays or other recursive data types?
    18)  How can I quote a variable to use in a regexp?
    19)  Why do setuid Perl scripts complain about kernel problems?
    20)  How do I open a pipe both to and from a command?
    21)  How can I change the first N letters of a string?
    22)  How can I manipulate fixed-record-length files?
    23)  How can I make a file handle local to a subroutine?
    24)  How can I extract just the unique elements of an array?
    25)  How can I call alarm() from Perl?
    26)  How can I test whether an array contains a certain element?
    27)  How can I do an atexit() or setjmp()/longjmp() in Perl?
    28)  Why doesn't Perl interpret my octal data octally?
    29)  Where can I get a perl-mode for emacs?
    30)  How can I use Perl interactively?
    31)  How do a sort an associative array by value instead of by key?
    32)  How can I capture STDERR from an external command?
    33)  Why doesn't open return an error when a pipe open fails?

To skip ahead to a particular question, such as question 17, you can
search for the regular expression "^17)".  Most pagers (more or less)
do this with the command /^17) followed by a carriage return.

1)  What is Perl?

    Here's the beginning of the description from the man page:

    Perl is an interpreted language optimized for scanning arbitrary text
    files, extracting information from those text files, and printing reports
    based on that information.  It's also a good language for many system
    management tasks.  The language is intended to be practical (easy to use,
    efficient, complete) rather than beautiful (tiny, elegant, minimal).  It
    combines (in the author's opinion, anyway) some of the best features of C,
    sed, awk, and sh, so people familiar with those languages should have
    little difficulty with it.  (Language historians will also note some
    vestiges of csh, Pascal, and even BASIC-PLUS.)  Expression syntax
    corresponds quite closely to C expression syntax.  Unlike most Unix
    utilities, Perl does not arbitrarily limit the size of your data--if
    you've got the memory, Perl can slurp in your whole file as a single
    string.  Recursion is of unlimited depth.  And the hash tables used by
    associative arrays grow as necessary to prevent degraded performance.
    Perl uses sophisticated pattern matching techniques to scan large amounts
    of data very quickly.  Although optimized for scanning text, Perl can also
    deal with binary data, and can make dbm files look like associative arrays
    (where dbm is available).  Setuid Perl scripts are safer than C programs
    through a dataflow tracing mechanism which prevents many stupid security
    holes.  If you have a problem that would ordinarily use sed or awk or sh,
    but it exceeds their capabilities or must run a little faster, and you
    don't want to write the silly thing in C, then Perl may be for you.  There
    are also translators to turn your sed and awk scripts into Perl scripts.

2)  Where can I get Perl?

    From any comp.sources.unix archive.  These machines, at the very least,
    definitely have it available for anonymous FTP:            

    If you are in Europe, you might using the following site.  This

    FTP: Perl stuff is in the UNIX directory on (

         path your_email_address
         send help
         send UNIX/INDEX
    The path-line may be omitted if your message contains a normal From:-line.
    You will receive a help-file and an index of the directory that contains
    the Perl stuff.

3)  How can I get Perl via UUCP?

    You can get it from the site osu-cis; here is the appropriate info,

    E-mail contact:
    Get these two files first:
    Current Perl distribution:

    How to reach osu-cis via uucp(L.sys/Systems file lines):
    # Direct Trailblazer
    osu-cis Any ACU 19200 1-614-292-5112 in:--in:--in: Uanon
    # Direct V.32 (MNP 4)
    # dead, dead, dead...sigh.
    #osu-cis Any ACU 9600 1-614-292-1153 in:--in:--in: Uanon
    # Micom port selector, at 1200, 2400, or 9600 bps.
    # Replace ##'s below with 12, 24, or 96 (both speed and phone number).
    osu-cis Any ACU ##00 1-614-292-31## "" \r\c Name? osu-cis nected \c GO \d\r\d\r\d\r in:--in:--in:

    Modify as appropriate for your site, of course, to deal with your
    local telephone system.  There are no limitations concerning the hours
    of the day you may call.

    Another possiblity is to use UUNET, although they charge you
    for it.  You have been duly warned.  Here's the advert:

               Anonymous Access to UUNET's Source Archives


         UUNET now provides access to its extensive collection of UNIX
    related sources to non- subscribers.  By  calling  1-900-468-7727
    and  using the login "uucp" with no password, anyone may uucp any
    of UUNET's on line source collection.  Callers will be charged 40
    cents  per  minute.   The charges will appear on their next tele-
    phone bill.

         The  file  uunet!~/help  contains  instructions.   The  file
    uunet!~/ls-lR.Z  contains  a complete list of the files available
    and is updated daily.  Files ending in Z need to be uncompressed
    before being used.   The file uunet!~/compress.tar is a tar
    archive containing the C sources for the uncompress program.

         This service provides a  cost  effective  way  of  obtaining
    current  releases  of sources without having to maintain accounts
    with UUNET or some other service.  All modems  connected  to  the
    900  number  are  Telebit T2500 modems.  These modems support all
    standard modem speeds including PEP, V.32 (9600), V.22bis (2400),
    Bell  212a  (1200), and Bell 103 (300).  Using PEP or V.32, a 1.5
    megabyte file such as the GNU C compiler would cost $10  in  con-
    nect  charges.   The  entire  55  megabyte X Window system V11 R4
    would cost only $370 in connect time.  These costs are less  than
    the  official  tape  distribution fees and they are available now
    via modem.

                      UUNET Communications Services
                   3110 Fairview Park Drive, Suite 570
                         Falls Church, VA 22042
                         +1 703 876 5050 (voice)
                          +1 703 876 5059 (fax)

4)  Where can I get more documentation and examples for Perl?

    If you've been dismayed by the ~75-page Perl man page (or is that man
    treatise?) you should look to ``the Camel Book'', written by Larry and

    Handbook by O'Reilly & Associates and entitled _Programming Perl_.
    Besides serving as a reference guide for Perl, it also contains
    tutorial material, is a great source of examples and cookbook
    procedures, as well as wit and wisdom, tricks and traps, pranks and
    pitfalls.  The code examples contained therein are available via
    anonymous FTP from in nutshell/perl/perl.tar.Z for your

    If you can't find the book in your local technical bookstore, the book
    may be ordered directly from O'Reilly by calling 1-800-dev-nuts if in
    North America (that's 1-800-338-6887 for those poor folks without
    handy mnemonic numbers on their phones) and 1-707-829-0515.
    Autographed copies are available from TECHbooks by calling

    regular version, 40$US for the special autographed one.

    The book's ISBN is

read more »

Sat, 02 Apr 1994 10:35:14 GMT  
 [ 4 post ] 

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