1st yr Exam revision thread - Scripts, C, Commands
Hello, I have an exam for 1st year Linux and Unix programming coming up in a week and I need some help going over the past exams, I want to make sure I'm getting the right answers in the past exams to ensure full marks.
The internet is a distraction so making this thread will hopefully help me focus! Also, it will be good revision for anyone else in the same boat, while hopfully helping me commit it to memory and understand it better, and the questions should be pretty easy
1. Write a bash script for the minimum program that works as follows:
Code:
$ min 2 3
The minimum of 2 and 3 is 2
Heres my answer:
Code:
#!/bin/bash
if
$1 < $2
echo "The minimum of $1 and $2 is $1"
else
echo "The minimum of $1 and $2 is $2"
fi
Pseudocode:
If
arg1 is less than arg2
output: "the minimum of arg1 and arg2 is arg1"
else
output: "the minimum of arg1 and arg2 is arg2"
Is my algorithm correct? The program compiles, but when I run it I get syntax error. What is the correct syntax please help.
---------- Post updated at 11:13 AM ---------- Previous update was at 10:43 AM ----------
Figured it out
Code:
if
[[ "$1" < "$2" ]];
then
echo "The minimum of $1 and $2 is $1"
else
echo "The minimum of $1 and $2 is $2"
fi
It works and outputs correctly. Do you think this answer would get full marks in an exam?
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Discussion started by: gurudewa
8 Replies
LEARN ABOUT SUSE
perlamiga
PERLAMIGA(1) Perl Programmers Reference Guide PERLAMIGA(1)NAME
perlamiga - Perl under Amiga OS
NOTE
Perl 5.8.0 cannot be built in AmigaOS. You can use either the maintenance release Perl 5.6.1 or the development release Perl 5.7.2 in
AmigaOS. See "PERL 5.8.0 BROKEN IN AMIGAOS" if you want to help fixing this problem.
SYNOPSIS
One can read this document in the following formats:
man perlamiga
multiview perlamiga.guide
to list some (not all may be available simultaneously), or it may be read as is: either as README.amiga, or pod/perlamiga.pod.
A recent version of perl for the Amiga can be found at the Geek Gadgets section of the Aminet:
http://www.aminet.net/~aminet/dev/gg
DESCRIPTION
Prerequisites for Compiling Perl on AmigaOS
Unix emulation for AmigaOS: ixemul.library
You need the Unix emulation for AmigaOS, whose most important part is ixemul.library. For a minimum setup, get the latest versions of
the following packages from the Aminet archives ( http://www.aminet.net/~aminet/ ):
ixemul-bin
ixemul-env-bin
pdksh-bin
Note also that this is a minimum setup; you might want to add other packages of ADE (the Amiga Developers Environment).
Version of Amiga OS
You need at the very least AmigaOS version 2.0. Recommended is version 3.1.
Starting Perl programs under AmigaOS
Start your Perl program foo with arguments "arg1 arg2 arg3" the same way as on any other platform, by
perl foo arg1 arg2 arg3
If you want to specify perl options "-my_opts" to the perl itself (as opposed to your program), use
perl -my_opts foo arg1 arg2 arg3
Alternately, you can try to get a replacement for the system's Execute command that honors the #!/usr/bin/perl syntax in scripts and set
the s-Bit of your scripts. Then you can invoke your scripts like under UNIX with
foo arg1 arg2 arg3
(Note that having *nixish full path to perl /usr/bin/perl is not necessary, perl would be enough, but having full path would make it easier
to use your script under *nix.)
Shortcomings of Perl under AmigaOS
Perl under AmigaOS lacks some features of perl under UNIX because of deficiencies in the UNIX-emulation, most notably:
o fork()
o some features of the UNIX filesystem regarding link count and file dates
o inplace operation (the -i switch) without backup file
o umask() works, but the correct permissions are only set when the file is finally close()d
INSTALLATION
Change to the installation directory (most probably ADE:), and extract the binary distribution:
lha -mraxe x perl-$VERSION-bin.lha
or
tar xvzpf perl-$VERSION-bin.tgz
(Of course you need lha or tar and gunzip for this.)
For installation of the Unix emulation, read the appropriate docs.
Accessing documentation
Manpages for Perl on AmigaOS
If you have "man" installed on your system, and you installed perl manpages, use something like this:
man perlfunc
man less
man ExtUtils.MakeMaker
to access documentation for different components of Perl. Start with
man perl
Note: You have to modify your man.conf file to search for manpages in the /ade/lib/perl5/man/man3 directory, or the man pages for the perl
library will not be found.
Note that dot (.) is used as a package separator for documentation for packages, and as usual, sometimes you need to give the section - 3
above - to avoid shadowing by the less(1) manpage.
Perl HTML Documentation on AmigaOS
If you have some WWW browser available, you can build HTML docs. Cd to directory with .pod files, and do like this
cd /ade/lib/perl5/pod
pod2html
After this you can direct your browser the file perl.html in this directory, and go ahead with reading docs.
Alternatively you may be able to get these docs prebuilt from "CPAN".
Perl GNU Info Files on AmigaOS
Users of "Emacs" would appreciate it very much, especially with "CPerl" mode loaded. You need to get latest "pod2info" from "CPAN", or,
alternately, prebuilt info pages.
Perl LaTeX Documentation on AmigaOS
Can be constructed using "pod2latex".
BUILDING PERL ON AMIGAOS
Here we discuss how to build Perl under AmigaOS.
Build Prerequisites for Perl on AmigaOS
You need to have the latest ixemul (Unix emulation for Amiga) from Aminet.
Getting the Perl Source for AmigaOS
You can either get the latest perl-for-amiga source from Ninemoons and extract it with:
tar xvzpf perl-$VERSION-src.tgz
or get the official source from CPAN:
http://www.cpan.org/src/5.0
Extract it like this
tar xvzpf perl-$VERSION.tar.gz
You will see a message about errors while extracting Configure. This is normal and expected. (There is a conflict with a similarly-named
file configure, but it causes no harm.)
Making Perl on AmigaOS
Remember to use a hefty wad of stack (I use 2000000)
sh configure.gnu --prefix=/gg
Now type
make depend
Now!
make
Testing Perl on AmigaOS
Now run
make test
Some tests will be skipped because they need the fork() function:
io/pipe.t, op/fork.t, lib/filehand.t, lib/open2.t, lib/open3.t, lib/io_pipe.t, lib/io_sock.t
Installing the built Perl on AmigaOS
Run
make install
PERL 5.8.0 BROKEN IN AMIGAOS
As told above, Perl 5.6.1 was still good in AmigaOS, as was 5.7.2. After Perl 5.7.2 (change #11423, see the Changes file, and the file
pod/perlhack.pod for how to get the individual changes) Perl dropped its internal support for vfork(), and that was very probably the step
that broke AmigaOS (since the ixemul library has only vfork). The build finally fails when the ext/DynaLoader is being built, and PERL
ends up as "0" in the produced Makefile, trying to run "0" does not quite work. Also, executing miniperl in backticks seems to generate
nothing: very probably related to the (v)fork problems. Fixing the breakage requires someone quite familiar with the ixemul library, and
how one is supposed to run external commands in AmigaOS without fork().
AUTHORS
Norbert Pueschel, pueschel@imsdd.meb.uni-bonn.de Jan-Erik Karlsson, trg@privat.utfors.se
SEE ALSO perl(1).
perl v5.12.1 2010-04-26 PERLAMIGA(1)
05-25-2013
