Standard Input / Output

Standard input

read

read [-r] [varname]*

• -r  : Backslash does not act as an escape character.
  

• Reads a line from standard input and stores it in the specified variables.
• If no variables are specified, the user input is stored in the special shell variable REPLY
• Stores one piece of data (text separated by white space) per variable, except for the last variable, which holds all remaining data from the line of user input.

echo Enter a value
read index
echo Input: $index

echo "Enter another value"
read
echo "Input: $REPLY"

# Read a file line-by-line
cat $file | while read line; do
    echo ${line}
done

Standard error

Suppressing errors

cmd 2> /dev/null   # Suppress error messages
cmd >& /dev/null   # Suppress error messages and standard output