Shell Programming and Scripting

Hi,

I am just trying to compare integer in ksh. can you please tell me what's wrong with this code... or give me suggestions on alternative.

sample code:

i=0;

if [ i -eq 0 ]; then
echo inside if
fi


Thanks in advance!

Try with below

Code:

i=0;
if [ $i -eq 0 ]; then
echo inside if
fi

In case you want to debug your script put below code at the very beginning

Code:

set -x

Cheers
Harish

For ksh, use the built-ins to save some processes and thus efficiency ('[' is an external program (test) and echo is also an external program, while '((' is built-in for math and print is built-in). While this example will not save much time, in a larger script or more complex script your savings will be significant:

Code:

#!/bin/ksh  

integer i=0;

if (( $i == 0 )); then
  print "inside if"
fi

(( )) is the best method - my opinion. You can use variable without $, about like in C.

Code:

y=100
(( a=y+2 ))
(( b=a+3 ))
if (( b < a )) ; then
   echo "b<a"
fi
(( b < a )) && echo "b<a" || echo "a<=b"
(( a= (b+100)*12 ))
# floating (LANG ... =>  , or . delimeter)
typeset -F2  l1 l2 l3 
l1=1.22 
l2=2.22 
(( l3=l1*l2)) 
echo $l3

Ofcourse you can use test command, but (( )) is nicer for numbers.

Not in any modern version of ksh. These have been builtins for a long time. Use the builtins command to see the default list of builtins in ksh.

Yes, old bourne shell not included [, echo, true, false, ... but long time in many shells has been builtin echo, test, true, false, ... = posix shells.
So [, test, [[, ((, echo, print, printf, true, false, :, .. are builtin.
=> sometimes works little different, options are not always same, and so on. Some has done
just like posix has written, some has addon options.

In history we used
:
in forever loops, but today you can use true, it's not anymore external and so on.

Awk, sed, cut, tr, grep, expr, ... are still externals.

Ex. in ksh you can use command builtin to look ksh builtin. Also ksh93 include some builtin manuals. No need to read ksh manual.

Code:

read --man
typeset --man
set --man