How do i use the read command to read from a file?

vaquitasos

As well as well as taking interactive input, the read command can read from a file too.

Take a look at the following script; the inputfile.txt is in the same directory as the script.

$ cat readthis.sh 
#!/bin/bash
while read line
do
   echo $line | sed -e 's/line/item/'
done < inputfile.txt

We read line by line and use the sed command to change a word. The change is not permanent. We just used sed to demonstrate a modification of the lines. Between the do and done you process $line however you want.