Read from a file and stdin in Bash

Question

I would like to know if I can write a shell script that accepts two arguments simultaneously, one from a file and the another one from stdin. Could you give some example please?.

I trying

while read line
   do
   echo "$line"
done < "${1}" < "{/dev/stdin}"

But this does not work.

Answer 1

You can use cat - or cat /dev/stdin:

while read line; do
  # your code
done < <(cat "$1" -)

or

while read line; do
  # your code
done < <(cat "$1" /dev/stdin)

or, if you want to read from all files passed through command line as well as stdin, you could do this:

while read line; do
  # your code
done < <(cat "$@" /dev/stdin)

---

See also:

• How to read from a file or stdin in Bash?