03-19-2006
Help understanding a program
I ran the following program. I don't understand some of it.
#!/bin/sh
case $1 in
--test|-t)
echo "you used the --test option"
exit 0
;;
--help|-h)
echo "Usage:"
echo " myprog.sh [--test|--help|--version]"
exit 0
;;
--version|-v)
echo "myprog.sh version 0.0.1"
exit 0
;;
-*)
echo "No such option $1"
echo "Usage:"
echo " myprog.sh [--test|--help|--version]"
exit 1
;;
esac
echo "You typed \"$1\" on the command-line"
-----------------------------------------------------------------------------
Do I need a program called '' myprog.sh '' to run this program?
I got the following message when running it.
You typed "" on the command-line.
The name of the program is '' temp25 '' .
[nissanka@c83-250-111-20 ~]$ chmod 755 temp25
[nissanka@c83-250-111-20 ~]$ ./temp25
You typed "" on the command-line
--------------------------------------------------
I have a file called '' Cisco ''
[nissanka@c83-250-111-20 ~]$ ./temp25 Cisco
You typed "Cisco" on the command-line
[nissanka@c83-250-111-20 ~]$
Could you please tell me how to run this program and how it works?
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LEARN ABOUT REDHAT
escape
escape(1) Mail Avenger 0.8.3 escape(1)
NAME
escape - escape shell special characters in a string
SYNOPSIS
escape string
DESCRIPTION
escape prepends a "" character to all shell special characters in string, making it safe to compose a shell command with the result.
EXAMPLES
The following is a contrived example showing how one can unintentionally end up executing the contents of a string:
$ var='; echo gotcha!'
$ eval echo hi $var
hi
gotcha!
$
Using escape, one can avoid executing the contents of $var:
$ eval echo hi `escape "$var"`
hi ; echo gotcha!
$
A less contrived example is passing arguments to Mail Avenger bodytest commands containing possibly unsafe environment variables. For
example, you might write a hypothetical reject_bcc script to reject mail not explicitly addressed to the recipient:
#!/bin/sh
formail -x to -x cc -x resent-to -x resent-cc
| fgrep "$1" > /dev/null
&& exit 0
echo "<$1>.. address does not accept blind carbon copies"
exit 100
To invoke this script, passing it the recipient address as an argument, you would need to put the following in your Mail Avenger rcpt
script:
bodytest reject_bcc `escape "$RECIPIENT"`
SEE ALSO
avenger(1),
The Mail Avenger home page: <http://www.mailavenger.org/>.
BUGS
escape is designed for the Bourne shell, which is what Mail Avenger scripts use. escape might or might not work with other shells.
AUTHOR
David Mazieres
Mail Avenger 0.8.3 2012-04-05 escape(1)