string comparison operators, what are they?? - Page 2 - Shell Programming and Scripting

vino · #8 02-13-2006

Quote:

Originally Posted by ballazrus

Code:

#! /bin/sh

read A B

if [ $A < $B ] ; then
        echo "$A is less than $B"
else
        echo "$A is greater than $B"
fi

exit 0

intranet (119) % sh strcmp.sh
hi bye
strcmp.sh: bye: cannot open <-- error message

so i'm using the < as a string operator but it detects it as a redirect.

and basically A and B are read in from the keyboard

thanks for your patience by the way, i know it's late, at least where i live hehe

Code:

#! /bin/sh

read A B

if [[ $A < $B ]] ; then
        echo "$A is less than $B"
else
        echo "$A is greater than $B"
fi

exit 0

ballazrus · #9 02-13-2006

i tried the other one too with the double brackets and it doesnt give me the right result. it does show an error but will go through the whole execution of the program, but as mentioned before, the result isn't correct

this is what happens

intranet (121) % sh strcmp.sh
hi bye
strcmp.sh: [[: not found
hi is greater than bye

intranet (122) % sh strcmp.sh
bye hi
strcmp.sh: [[: not found
bye is greater than hi

so in the first run, i type in hi and bye, it says the [[ part of the code not found...i take it that it cant interpret double brackets.

and it goes to the else statement.

in the second run i type in bye before hi, and it goes to the else statement again, while it should've been the first if statement.

i'm going to have to try it out on a real c shell to see what the result turns out to be.

vino · #10 02-13-2006

I guess it must have something to do with the vmware machine.

ballazrus · #11 02-13-2006

i'mnot using it with vmware at the moment, but i'm using SPARC, i think it's based on unix, hence why it keeps interpreting the > and < as redirect. however the double brackets arent working either. i found another forum where a user had posted his code which looks just like the one with the double brackets and he's having the same problem.

i will have to test both codes tomorrow on my school's vmware.

ballazrus · #12 02-13-2006

hi, vino, i just wanted to say thanks for your help. i d/led cygwin and ran the code for the double brackets and it works like a charm. i think cygwin is a c shell emulator? or perhaps bourne shell. either way it's working great.

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