Shell Programming and Scripting

Hi All,

Does anyone know how to read multiple lines from standard input into an array and then iterate a loop for all the lines read. Below is an example pseudocode:


I need the below filenames to be read by the script into an array or something similar:


And then in the script, I would need to iterate for each file:

Code:

For each filename

Do processing of the current file

End For

Is there anyway to do the above in UNIX. Please help!

This is a sample code

Code:

declare -a array[10]

for i in seq 1 3
do
read array[$i]
done

for i in seq 1 3
do
echo  -e "${array[$i]}\n " ;
done

You try the following script.This script will read the filenames from user and print the content of filenames in stdout.

Code:

i=0
echo "Enter The number of filenames to read:"
read n
for((i=0;i<$n;i++))
do
echo -n "Enter Filename:"
read file
filenames[$i]=$file
done
for((i=0;i<$n;i++))
do
echo -e "--------------------------\n\tFILE:${filenames[$i]}\t\n--------------------------"
cat ${filenames[$i]}
done

To read from stdin just try the following way,After getting all the lines just perss ctrl+d to stop.

Code:

i=1
while read line
do
    array[ $i ]="$line"
    (( i++ ))
done
echo " --------------- "
j=1;
while [ $j -le $i ]
do
        echo ${array[ $j ]}
        let j=$j+1
done

Try this

Code:

#!/bin/sh
i=0;
while read file
do
        file_array[$i]=$file
        i=`expr $i + 1`
done
N=${#file_array[@]}

for (( j=0; j<N; j++))
do
        echo -e "\n\tFILE NAME : ${file_array[$j]}\t\n"
done

Thanks all for your reply!

Ok, I think I left 1 requirement in my first post. I am going to get my filenames (inputs) thru email and there are going to be a lot of filenames (and NO constant count on number of files) which I would be passing to the script for processing.

I was thinking if I can just copy and paste all the filenames into the standard input and read it in my script thru an array/any-other way and process them each in a loop.

I have tried the above examples but in which I was not able to paste all the filenames at a single shot! When I do paste, after the first line since there is a return key in the list of filenames, the script breaks.

Please help me do this! Let me know if you have any questions!

---------- Post updated at 12:16 AM ---------- Previous update was at 12:10 AM ----------

Simply put, the read command, I believe, reads only one line from the Standard Input. So, I will end up giving my filename list one by one which I will not be able to do as the list is huge. Is there a way to read multiple lines from Std input at a single stretch?

It will make more sense to paste the contents into a separate file and then read the file line by line in your script.

Code:

while read file
do
[your logic here]
done < inputfile