read - Reads a line from standard input
read [-r] var...
Interfaces documented on this reference page conform to
industry standards as follows:
read: XCU5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Do not treat a backslash character in any special way.
Consider each backslash to be part of the input line.
Note
The -r option is included to enable read to subsume
the purpose of the obsolete line utility.
The name of an existing or non-existing shell variable.
The read utility reads 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 invoking shell is interactive,
read prompts for a continuation line in the following
cases: 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 is split into fields as in the shell (see the
sh(1) reference page); the first field is assigned to the
first variable var, the second field to the second variable
var, and so forth. If there are fewer var parameters
specified than there are fields, the leftover fields and
their intervening separators are assigned to the last var.
If there are fewer fields than vars, the remaining vars
are set to empty strings.
The setting of variables specified by the var parameters
affects the current shell execution environment. If read
is called in a subshell or separate utility execution
environment, such as one of the following, it does not
affect the shell variables in the caller's environment:
(read foo) nohup read ... find . -exec read ... \;
The -r option is included to enable read to subsume the
purpose of the obsolete line utility.
The results are undefined if an end-of-file is detected
following a backslash at the end of a line when -r is not
specified.
The following exit values are returned: Successful completion.
End-of-file was detected or an error occurred.
The following command prints a file with the first field
of each line moved to the end of the line:
while read -r xx yy do
printf "%s %s\n" "$yy" "$xx" done < input_file
ENVIRONMENT VARIABLES [Toc] [Back] The following environment variables affect the execution
of read: Determines the internal field separators used to
delimit fields. Provides a default value for the internationalization
variables that are unset or null. If LANG
is unset or null, the corresponding value from the default
locale is used. If any of the internationalization variables
contain an invalid setting, the utility behaves as
if none of the variables had been defined. If set to a
non-empty string value, overrides the values of all the
other internationalization variables. Determines the
locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as
opposed to multibyte characters in arguments). Determines
the locale used to affect the format and contents of diagnostic
messages written to standard error. Determines the
location of message catalogues for the processing of
LC_MESSAGES. 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-document is not terminated after a newline
character is entered.
Commands: line(1)
Functions: fread(3)
Standards: standards(5)
read(1)
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