read

Examples

Store input on default variable

Press enter (newline) to complete the input.

$ echo -n "Enter some text > "
$ read
Hello

$ echo "You entered: $REPLY"
You entered: Hello

Store input as variable

$ echo -n "Enter some text > "
$ read TEXT
$ echo "You entered: $TEXT"

Evaluate response

For maths, use the $(( EXPRESSION )) syntax.

read NUMBER
if [ $((NUMBER % 2)) -eq 0 ]; then
    echo "Number is even"
else
    echo "Number is odd"
fi

Common flags

Show message

• -p - Print prompt, without newline.

This also avoids using echo.

$ read -p "Enter some text > "

Timeout

• -t timeout - time out and return failure if a complete line of input is not read within TIMEOUT seconds

if read -t 3; then
    echo "Great, you made it in time!"
else
    echo "Sorry, you are too slow!"
fi

Hide input

• -s - do not echo input coming from a terminal

This is useful if you capture a password and don’t want to display it.

Help

Manpage

NAME
    read - Read a line from the standard input and split it into fields.

SYNOPSIS
    read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]

DESCRIPTION
    Read a line from the standard input and split it into fields.

    Reads a single line from the standard input, or from file descriptor FD
    if the -u option is supplied.  The line is split into fields as with word
    splitting, and the first word is assigned to the first NAME, the second
    word to the second NAME, and so on, with any leftover words assigned to
    the last NAME.  Only the characters found in $IFS are recognized as word
    delimiters.

    If no NAMEs are supplied, the line read is stored in the REPLY variable.

    Options:
      -a array	assign the words read to sequential indices of the array
    		variable ARRAY, starting at zero
      -d delim	continue until the first character of DELIM is read, rather
    		than newline
      -e	use Readline to obtain the line
      -i text	use TEXT as the initial text for Readline
      -n nchars	return after reading NCHARS characters rather than waiting
    		for a newline, but honor a delimiter if fewer than
    		NCHARS characters are read before the delimiter
      -N nchars	return only after reading exactly NCHARS characters, unless
    		EOF is encountered or read times out, ignoring any
    		delimiter
      -p prompt	output the string PROMPT without a trailing newline before
    		attempting to read
      -r	do not allow backslashes to escape any characters
      -s	do not echo input coming from a terminal
      -t timeout	time out and return failure if a complete line of
    		input is not read within TIMEOUT seconds.  The value of the
    		TMOUT variable is the default timeout.  TIMEOUT may be a
    		fractional number.  If TIMEOUT is 0, read returns
    		immediately, without trying to read any data, returning
    		success only if input is available on the specified
    		file descriptor.  The exit status is greater than 128
    		if the timeout is exceeded
      -u fd	read from file descriptor FD instead of the standard input

    Exit Status:
    The return code is zero, unless end-of-file is encountered, read times out
    (in which case it's greater than 128), a variable assignment error occurs,
    or an invalid file descriptor is supplied as the argument to -u.