Content-type: text/html Man page of read

read

Section: User Commands (1)
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NAME

read - Reads a line from standard input  

SYNOPSIS

read [-r] var...


 

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

read:  XPG4, XPG4-UNIX

Refer to the standards(5) reference page for more information about industry standards and associated tags.
 

OPTIONS

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.

 

OPERANDS

The name of an existing or non-existing shell variable.
 

DESCRIPTION

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 ... \;


 

NOTES

The -r option is included to enable read to subsume the purpose of the obsolete line utility.
 

RESTRICTIONS

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.
 

EXIT STATUS

The following exit values are returned: Successful completion. End-of-file was detected or an error occurred.
 

EXAMPLES

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

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.
 

SEE ALSO

Commands:  line(1)

Functions:  fread(3)

Standards:  standards(5)


 

Index

NAME
SYNOPSIS
STANDARDS
OPTIONS
OPERANDS
DESCRIPTION
NOTES
RESTRICTIONS
EXIT STATUS
EXAMPLES
ENVIRONMENT VARIABLES
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 02:42:57 GMT, October 02, 2010