Very Computer

Hi all -

This is a silly question, and if I had my shell scripting book here at
the house instead of at the office, I would just RTFM.

I have a script that is doing something like:

x=1
while $x -lt 100000; do
  x=$x+1
  exho $x
done

So that I get 1, then 2, then 3, then 4, etc.  Obviously, I am doing it
wrong, because I am gettin 1, then 1+1, then 1+1+1, etc.

What am I doing wrong?

Thanks!
Thomas

Quote:>blush<

Should be:

#!/bin/sh
x=1
while test $x -lt 100000; do
   let x=$x+1
   echo $x
done

Thanks for the help!
Thomas

: >blush<
: Thanks, Shawn Everett for answering, and making all clear...
: Should be:
: #!/bin/sh
: x=1
: while test $x -lt 100000; do
:    let x=$x+1
:    echo $x
: done

There is a definite problem with this. While it is true that in
_kornshell_ the above will work (and BTW is a sub-optimal solution)
there is no builtin arithmetric operators in /bin/sh, as you state
explicitly above.

Although in the very newest OSes, ksh93 is frequently called /bin/sh,
I would instead have you understand the confusion that will be
inevitably caused by your assertion above.

#!/bin/ksh
typeset -i x=0
while (((x+=1)<100000))
do      print -- $x
done

-James

(James R. Martin) posted to comp.unix.shell:

 > : #!/bin/sh
 > : x=1
 > : while test $x -lt 100000; do
 > :    let x=$x+1
 > :    echo $x
 > : done
 > There is a definite problem with this. While it is true that in
 > _kornshell_ the above will work (and BTW is a sub-optimal solution)
<...>
 > #!/bin/ksh
 > typeset -i x=0
 > while (((x+=1)<100000))
 > do        print -- $x
 > done

The canonical /bin/sh solution is to use the expr(1) to update the
variable:

    #!/bin/sh
    x=1
    while [ $x -lt 100000 ]; do
        x=`expr $x + 1`  # Spaces around plus sign are significant
        echo $x          # Is the intent really to echo 2 .. 100000??
    done

It recently occurred to me that you might instead use a generator
program of some sort to drive the loop, and save a bunch of processes:

    #!/bin/sh
    perl -e 'for ($x = 1; $x < 100000; ++$x) { print "$x\n" }' |
    while read x; do
      echo "$x"
    done

This can probably be solved more neatly with something markedly
simpler than Perl as the driver but I think you should already find
this to be more efficient on most systems. (Anybody wanna test?)

/* era */

What would be a good way to generate successive integers? bc(1)?
tr '\000' '\012' </dev/zero | head -100000 | nl -b a? :-)

--
 Paparazzi of the Net: No matter what you do to protect your privacy,
  they'll hunt you down and spam you. <http://www.iki.fi/~era/spam/>

Quote:>It recently occurred to me that you might instead use a generator
>program of some sort to drive the loop, and save a bunch of processes:

>    #!/bin/sh
>    perl -e 'for ($x = 1; $x < 100000; ++$x) { print "$x\n" }' |
>    while read x; do
>      echo "$x"
>    done

>This can probably be solved more neatly with something markedly
>simpler than Perl as the driver