I'm new in shell programming ... basically I'm novice at all but I need a simple script to do while loop and execute a php script . I've tried the following :
!/bin/bash
i=0
while[ i < 13 ]
do
php /var/www/html/pos.php &
(( i++ ))
done
but for some reasons the syntax is not good ... I'm getting error line 4: syntax error near unexpected token `do'
You need to have a space between while and the left bracket [, and you need to put the do on a separate line or use a semicolon (both of those are fairly common mistakes when writing loops). Additionally, the left bracket [ is equivalent to man test which supports -lt but not <:
function doStuff() {
local counter=0
while [ $counter -lt 10 ]
do
echo $counter
let counter=$counter+1
done
}
doStuff
OR
function doStuff() {
local counter=0
while [ $counter -lt 10 ] ; do
echo $counter
let counter=$counter+1
done
}
doStuff
!/bin/bash
i=0
while (( i < 13 ))
do
php /var/www/html/pos.php &
(( i++ ))
done
alternatively, you can use a for loop
for((i=1;i<=13;i++))
do
php /var/www/html/pos.php &
done
since the for loop already creates the counter you, you don't have to declare a counter manually.
can't see your code, but it should be like this
while [ $i -ne 3 ]
do
echo "on number $i of 3"
i=`expr $i + 1`
done
expr since bash shell supports internal maths for addition
(( )) is not portable as well, at least not on bourne shell, yet many solutions posted includes that. Are you going to comment on them one by one? 2nd, if everyone writes portable code, then their code must at least able to work on the old bourne shell. Why regress, instead of progress? If it was me, I won't recommend using shell language at all. Lastly, "usefulness of the code" ? expr is external, for efficiency, I would use internals instead. I find it useless to "argue" with you further on this.I suppose that you want to do something like:
i=0; while (($i<10)); do i=$((i+1)); echo $i; done
#!. Because you have no space (the shell will be looking for a commandwhile[, which probably does not exist), thedois an unexpected keyword - there is no preceding loop that requires it, so you get the syntax error.