Read one line from the standard input, (or from a file) and assign the word(s) to variable name(s).
Syntax read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-r] [-s] [-t timeout] [-u fd] [name...] Key -a aname The words are assigned to sequential indices of the array variable aname, starting at 0. aname is unset before any new values are assigned. Other name arguments are ignored. -d delim The first character of delim is used to terminate the input line, rather than newline. -e If the standard input is coming from a terminal, readline is used to obtain the line. -i text If readline is being used to read the line, text is placed into the editing buffer before editing begins. -n nchars read returns after reading nchars characters rather than waiting for a complete line of input. -N nchars read returns after reading exactly nchars characters rather than waiting for a complete line of input, unless EOF is encountered or read times out. Delimiter characters encountered in the input are not treated specially and do not cause read to return until nchars characters are read. -p prompt Display prompt on standard error, without a trailing newline, before attempting to read any input. The prompt is displayed only if input is coming from a terminal. -r Do not treat a Backslash as an escape character. The backslash is considered to be part of the line. In particular, a backslash-newline pair can not be used as a line continuation. Without this option, any backslashes in the input will be discarded. You should almost always use the -r option with read. -s Silent mode. If input is coming from a terminal, characters are not echoed. -t timeout Cause read to time out and return failure if a complete line of input is not read within timeout seconds. This option has no effect if read is not reading input from the terminal or a pipe. -u fd Read input from file descriptor fd. name The name(s) to assign to each word. If no names are supplied, the line read is assigned to the variable $REPLY.
This is a BASH shell builtin, to display your local syntax from the bash prompt type: help [r]ead
One line is read from the standard input, and the first word is assigned to the first name, the second word to the second name, and so on, with leftover words and their intervening separators assigned to the last name.
The read command modifies each line read; by default it removes all leading and trailing whitespace characters (spaces and tabs, or any whitespace characters present in IFS). If that is not desired, the IFS variable can be cleared with IFS=
If there are fewer words read from the standard input than names, the remaining names are assigned empty values.
The characters in the value of the IFS variable are used to split the line into words.
The backslash character '\' can be used to remove any special meaning for the next character read, and for line continuation.
The return code is zero, unless end-of-file is encountered or read
times out.
Loop through a text file 'demo.txt' and print each line:
while IFS= read -r line; do
echo "Line: $line"
done <demo.txt
Prompt for some values and then display on screen horizontally and then vertically:
#!/bin/bash
# Read a value and save to the variable $var_year
read var_year
echo "The year is: $var_year"# Read a value and save to the variable $var_name
echo "Enter your name and press [ENTER]: "
read var_name
echo "Your name is: $var_name"# Read a value using the default variable $REPLY
$ read
$ echo You entered $REPLY# Read a password value from input and then set a default '1234' if it is empty:
read passw
passw="${passw:=1234}"# Set a variable 'ret1' to four different values in turn, and just echo each to the screen:
$ echo "First Second Third Fourth " | while read -r -d ' ' ret1; do printf "=$ret1="; done =First==Second==Third==Fourth=# as above but adding a newline '\n':
$ echo "First Second Third Fourth " | while read -r -d ' ' ret1; do printf "=$ret1= \n"; done
=First=
=Second=
=Third=
=Fourth=
"Programs are meant to be read by humans and only incidentally for computers to execute" ~ Donald Knuth
mapfile - Read lines from standard input into an indexed array variable.
select - Accept keyboard input.
Equivalent Windows commands:
SET /P - Prompt for user input.