[ale] Bash script

[Mark J. Reed]

Sure, easy.  If CDROM is null, then 
	[ -n $CDROM ]
expands to just
	[ -n ]

since the "-n" test flag requires an argument, bash complains.  To
solve this, put the $CDROM inside double quotes.  Then

	[ -n "$CDROM" ]
expands to
	[ -n "" ]

and the shell is happy.  As a general rule, any time you're expanding a
shell variable, put double-quotes around the expansion, unless you
explicitly want its value to be split up by whitespace and neither you
nor the shell cares if it's null.

David Hamm writes:
\ I am developing a genuine hate for the bash parser
\ the following shell script creats the output listed below it.  The
\ script works but it emits an error.  Can anyone tell me where I'm going
\ wrong?

\ ********** the shell script
\ #!/bin/sh
\ CDROM=`grep cdrom /etc/mtab`
\ if [ -n $CDROM ]; then
\         echo Mounting Cdrom under /cdrom
\         mount -r -t iso9660 /dev/cdrom /cdrom
\ 
\ else
\         echo Unmounting Cdrom mounted under /cdrom
\         umount /cdrom
\         sleep 1
\         eject
\ fi                  
\
\ ******** the output **********
\ /usr/bin/cdrom: [: too many arguments
\ Unmounting Cdrom mounted under /cdrom

-- 
Mark J. Reed
Email: mark_reed at sware.com - Voice: +1 404 315 6296 x158 - Fax: +1 404 315 6407
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