Simple for loop question - Shell Programming and Scripting

arex876 · #1 07-23-2008

Hello

I am a beginner of shell scripting and i am having trouble to do a for loop.

I want a for loop to do stuff 3 times.

i.e.

in visual basic i do this
for (counter = 0; counter < 3; counter++)

on my shell script i have something like this at the moment

server=/apps/scripts/server.txt
servercount=$(wc -l <$server) #It has 3 lines
for i in $servercount
do
Echo $i
done

When i run this shell script, it only shows me 3.. but i want it to show
1
2
3

I also tried

for (( j = 1 ; j <= 3; j++ ))
do
echo $j
done

but i got an error
test2.txt: line 4: syntax error near unexpected token `(('
test2.txt: line 4: `for ((i = 1;i<= 3;i++))'

done

jim mcnamara · #2 07-23-2008

Code:

while read i 
do 
   echo "$i"
done <  $server

do not use a for loop, you are reading multiple lines from the file.

Ikon · #3 07-23-2008

This should get you started:

Code:

for i in 1 2 3 4 5
do
echo "Welcome $i times"
done

your code is basically:

Code:

for i in 3
do
echo "Welcome $i times"
done

joeyg · #4 07-23-2008

I think your script ran fine because $servercount only contains one line entry.

sample code follows:

Code:

while read zf
  do
  echo $zf
done < server.txt

arex876 · #5 07-23-2008

Hey guys

My script only shows the result "3" instead of "1" "2" "3" on each line.
and i know why it does not work because I used the wrong code at first.

I still don't know why the following code is not working for me... i got a syntax error

for (( j = 1 ; j <= 3; j++ ))
do
echo -n $j
done

arunsoman80 · #6 07-23-2008

Use While loop.

server=/apps/scripts/server.txt
servercount=`wc -l <$server`
typeset -i i=1
while [ $i -le $servercount ]
do
echo $i
(( i = $i + 1 ))
done

Ikon · #7 07-23-2008

Code:

for (( j = 1 ; j <= 3; j++ )) 
do
echo -n $j
done

That works for me on CentOs. I get 123

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