read(1) User Commands read(1)NAMEread - read a line from standard input
SYNOPSIS
/usr/bin/read [-r] var...
sh
read name...
csh
set variable = $<
ksh
read [ -prsu [n]] [ name ? prompt] [name...]
DESCRIPTION
/usr/bin/read
The read utility will read a single line from standard input.
By default, unless the -r option is specified, backslash (\) acts as an
escape character. If standard input is a terminal device and the invok‐
ing shell is interactive, read will prompt for a continuation line
when:
· The shell reads an input line ending with a backslash, unless the
-r option is specified.
· A here-document is not terminated after a NEWLINE character is
entered.
The line will be split into fields as in the shell. The first field
will be assigned to the first variable var, the second field to the
second variable var, and so forth. If there are fewer var operands
specified than there are fields, the leftover fields and their inter‐
vening separators will be assigned to the last var. If there are fewer
fields than vars, the remaining vars will be set to empty strings.
The setting of variables specified by the var operands will affect the
current shell execution environment. If it is called in a subshell or
separate utility execution environment, such as one of the following:
(read foo)
nohup read ...
find . -execread ... \;
it will not affect the shell variables in the caller's environment.
The standard input must be a text file.
sh
One line is read from the standard input and, using the internal field
separator, IFS (normally space or tab), to delimit word boundaries, the
first word is assigned to the first name, the second word to the second
name, and so on, with leftover words assigned to the last name. Lines
can be continued using \newline. Characters other than NEWLINE can be
quoted by preceding them with a backslash. These backslashes are
removed before words are assigned to names, and no interpretation is
done on the character that follows the backslash. The return code is 0,
unless an end-of-file is encountered.
csh
The notation:
set variable = $<
loads one line of standard input as the value for variable. (See
csh(1)).
ksh
The shell input mechanism. One line is read and is broken up into
fields using the characters in IFS as separators. The escape character,
(\), is used to remove any special meaning for the next character and
for line continuation. In raw mode, -r, the \ character is not treated
specially. The first field is assigned to the first name, the second
field to the second name, and so on, with leftover fields assigned to
the last name. The -p option causes the input line to be taken from the
input pipe of a process spawned by the shell using |&. If the -s flag
is present, the input will be saved as a command in the history file.
The flag -u can be used to specify a one digit file descriptor unit n
to read from. The file descriptor can be opened with the exec special
command. The default value of n is 0. If name is omitted, REPLY is used
as the default name. The exit status is 0 unless the input file is not
open for reading or an end-of-file is encountered. An end-of-file with
the -p option causes cleanup for this process so that another can be
spawned. If the first argument contains a ?, the remainder of this
word is used as a prompt on standard error when the shell is interac‐
tive. The exit status is 0 unless an end-of-file is encountered.
OPTIONS
The following option is supported:
-r Does not treat a backslash character in any special way. Con‐
siders each backslash to be part of the input line.
OPERANDS
The following operand is supported:
var The name of an existing or non-existing shell variable.
EXAMPLES
Example 1: An example of the read command
The following example for /usr/bin/read prints a file with the first
field of each line moved to the end of the line:
example% while read-r xx yy
do
printf "%s %s\n" "$yy" "$xx"
done < input_file
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables
that affect the execution of read: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.
IFS Determines the internal field separators used to delimit
fields.
PS2 Provides the prompt string that an interactive shell will
write to standard error when a line ending with a backslash is
read and the -r option was not specified, or if a here-docu‐
ment is not terminated after a newline character is entered.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 End-of-file was detected or an error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOcsh(1), ksh(1), line(1), set(1), sh(1), attributes(5), environ(5),
standards(5)SunOS 5.10 28 Mar 1995 read(1)
