A common thing in shell scripting. I came across this script that will be useful for people learning to write script.
#!/usr/bin/ksh
#
# SCRIPT: 12_ways_to_parse.ksh.ksh
#
#
# REV: 1.2.A
#
# PURPOSE: This script shows the different ways of reading
# a file line by line. Again... (0 Replies)
Backlinks are super important on the web today! Without them your site most likely will not get found by search engine spiders. If your website has been generating low to No traffic then it is probably due to the lack of backlinks.
Below are 10 e-ffective Ways to Get Backlinks!
1. Forum... (0 Replies)
This is my first post here so hello everyone! I know that a command of the programs name can start a program and clicking on a icon in GUI can as well as a startup shell script but how do I educate myself of the method that starts an application? Does the GUI run a script? What are the ways/ way... (2 Replies)
Hi!
I really need your help!
I need to operate the columns separate by ',' of a file with this structure
a1,a2,a3
b1,b2,b3,b4,b5
c1,c2
d1,d2,d3
e1
....
and I want the result of this subtractions
a1-a1,a2-a1,a3-a1
b1-b1,b2-b1,b3-b1,b4-b1,b5-b1 (10 Replies)
How does X windows system launch a program?
Does X give init a command (fork) or does x give BASH a command? Can/does X interact with init directly or does everything go through BASH? :wall:
Thanks in advance! (4 Replies)
I guess I probably ask a dumb question but why use RADIUS for authentication as there are many ways to do it, as authentication is basically a user/password check?
What is the benifit(s) of using it ?
Thanks! (3 Replies)
I am trying to figure out the OS version of my Linux box. I got three commands:
# uname -a
Linux test01 2.6.18-238.el5 #1 SMP Thu Jan 13 15:51:15 EST 2011 x86_64 x86_64 x86_64
# cat /proc/version
Linux version 2.6.18-238.el5 (mockbuild@builder10.centos.org) (gcc version 4.1.2 20080704... (4 Replies)
to get the checksum of a file on unix systems, you can just use the "cksum" command.
i discovered there are some watered down versions of unix systems i have to do some work on. surprisingly, these systems have perl installed on them and awk.
so if the cksum command is not available on a... (1 Reply)
Discussion started by: SkySmart
1 Replies
LEARN ABOUT OSX
getopt
GETOPT(1) BSD General Commands Manual GETOPT(1)NAME
getopt -- parse command options
SYNOPSIS
args=`getopt optstring $*` ; errcode=$?; set -- $args
DESCRIPTION
The getopt utility is used to break up options in command lines for easy parsing by shell procedures, and to check for legal options.
Optstring is a string of recognized option letters (see getopt(3)); if a letter is followed by a colon, the option is expected to have an
argument which may or may not be separated from it by white space. The special option '--' is used to delimit the end of the options. The
getopt utility will place '--' in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments ($1 $2
...) are reset so that each option is preceded by a '-' and in its own shell argument; each option argument is also in its own shell argu-
ment.
EXAMPLES
The following code fragment shows how one might process the arguments for a command that can take the options -a and -b, and the option -o,
which requires an argument.
args=`getopt abo: $*`
# you should not use `getopt abo: "$@"` since that would parse
# the arguments differently from what the set command below does.
if [ $? != 0 ]
then
echo 'Usage: ...'
exit 2
fi
set -- $args
# You cannot use the set command with a backquoted getopt directly,
# since the exit code from getopt would be shadowed by those of set,
# which is zero by definition.
for i
do
case "$i"
in
-a|-b)
echo flag $i set; sflags="${i#-}$sflags";
shift;;
-o)
echo oarg is "'"$2"'"; oarg="$2"; shift;
shift;;
--)
shift; break;;
esac
done
echo single-char flags: "'"$sflags"'"
echo oarg is "'"$oarg"'"
This code will accept any of the following as equivalent:
cmd -aoarg file file
cmd -a -o arg file file
cmd -oarg -a file file
cmd -a -oarg -- file file
SEE ALSO sh(1), getopt(3)DIAGNOSTICS
The getopt utility prints an error message on the standard error output and exits with status > 0 when it encounters an option letter not
included in optstring.
HISTORY
Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. Example changed in FreeBSD
version 3.2 and 4.0.
BUGS
Whatever getopt(3) has.
Arguments containing white space or embedded shell metacharacters generally will not survive intact; this looks easy to fix but isn't. Peo-
ple trying to fix getopt or the example in this manpage should check the history of this file in FreeBSD.
The error message for an invalid option is identified as coming from getopt rather than from the shell procedure containing the invocation of
getopt; this again is hard to fix.
The precise best way to use the set command to set the arguments without disrupting the value(s) of shell options varies from one shell ver-
sion to another.
Each shellscript has to carry complex code to parse arguments halfway correcty (like the example presented here). A better getopt-like tool
would move much of the complexity into the tool and keep the client shell scripts simpler.
BSD April 3, 1999 BSD