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In this section you'll find for, while and until loops.
The for loop is a little bit different from other programming
languages. Basically, it let's you iterate over a series of
'words' within a string.
The while executes a piece of code if the control expression
is true, and only stops when it is false (or a explicit break is found
within the executed code.
The until loop is almost equal to the while loop, except that
the code is executed while the control expression evaluates to false.
If you suspect that while and until are very similar you are right.
#!/bin/bash
for i in $( ls ); do
echo item: $i
done
On the second line, we declare i to be the variable that
will take the
different values contained in $( ls ).
The third line could be longer if needed, or there could
be more lines
before the done (4).
'done' (4) indicates that the code that used the value of $i has
finished and $i can take a new value.
This script has very little sense, but a more useful way to use the
for loop would be to use it to match only certain files on the previous
example
fiesh suggested adding this form of looping. It's a for loop
more similar to C/perl... for.
#!/bin/bash
for i in `seq 1 10`;
do
echo $i
done
#!/bin/bash
COUNTER=0
while [ $COUNTER -lt 10 ]; do
echo The counter is $COUNTER
let COUNTER=COUNTER+1
done
This script 'emulates' the well known
(C, Pascal, perl, etc) 'for' structure
#!/bin/bash
COUNTER=20
until [ $COUNTER -lt 10 ]; do
echo COUNTER $COUNTER
let COUNTER-=1
done
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