read - Read Input

Read a line of input into variables.

Source: src/scripting/read_builtin.f90:builtin_read

Synopsis

read [-ptsrdan] [variable...]

Description

Reads a single line from standard input (or the specified file descriptor) and assigns words to variables. If no variable names are given, the line is stored in REPLY.

Options

Option	Description
`-p prompt`	Display prompt before reading
`-t timeout`	Timeout in seconds (returns 1 on timeout)
`-s`	Silent mode (no echo, for passwords)
`-r`	Raw mode (don't interpret backslashes)
`-d delim`	Use delim as line delimiter instead of newline
`-a array`	Read words into indexed array
`-n nchars`	Read at most nchars characters

Arguments

Argument	Description
variable	Variable name(s) to receive input
(none)	Input stored in REPLY

Word Splitting

Input is split according to IFS (default: space, tab, newline):

First word → first variable
Second word → second variable
...
Remaining words → last variable

Return Value

Code	Meaning
0	Success
1	End of file, timeout, or error

Examples

Basic reading

read name
echo "Hello, $name"

# With prompt
read -p "Enter your name: " name

# Multiple variables
read first last
echo "First: $first, Last: $last"

Password input

read -sp "Password: " password
echo  # newline after silent input

Timeout

if read -t 5 -p "Quick! Answer: " answer; then
    echo "You said: $answer"
else
    echo "Too slow!"
fi

Reading into array

read -a words <<< "one two three"
echo "${words[0]}"  # one
echo "${words[1]}"  # two
echo "${words[2]}"  # three

Custom delimiter

# Read until comma
read -d ',' field1 <<< "value1,value2,value3"
echo "$field1"  # value1

Raw mode (preserve backslashes)

# Without -r: backslash is escape
echo "path\\to\\file" | read line
echo "$line"  # path\to\file (backslashes eaten)

# With -r: literal backslashes
echo "path\\to\\file" | read -r line
echo "$line"  # path\\to\\file (preserved)

Read specific number of characters

read -n 1 -p "Press any key to continue..."
echo

Implementation Details

From read_builtin.f90:

! Parse options
do while (i <= num_args)
    arg = args(i)
    select case (trim(arg))
    case ("-p")
        prompt = args(i + 1)
        i = i + 2
    case ("-t")
        timeout_seconds = parse_integer(args(i + 1))
        i = i + 2
    case ("-s")
        silent_mode = .true.
        i = i + 1
    case ("-r")
        raw_mode = .true.
        i = i + 1

For silent mode, terminal echo is disabled:

if (silent_mode) then
    call disable_echo()
end if
! ... read input ...
if (silent_mode) then
    call enable_echo()
end if

IFS Behavior

Word splitting respects IFS:

# Default IFS (space, tab, newline)
echo "  one   two   three  " | read a b c
# a="one", b="two", c="three"

# Custom IFS
IFS=: read user x uid gid gecos home shell < /etc/passwd
# Splits on colons

# Empty IFS (no splitting)
IFS= read -r line < file
# Entire line in one variable

Reading Files

# Read line by line
while IFS= read -r line; do
    echo "Line: $line"
done < file.txt

# Read specific fields
while IFS=: read -r user _ uid gid _ home shell; do
    echo "$user uses $shell"
done < /etc/passwd

Related Commands

echo - Output text
printf - Formatted output

Notes

Without -r, backslash-newline continues to the next line
The last variable receives all remaining words
read reads from stdin by default; use redirection for files
For passwords, combine -s (silent) with -p (prompt): read -sp "Password: "
Timeout only works in interactive terminals, not in pipes