mirror of https://github.com/mkerrisk/man-pages
175 lines
5.0 KiB
Groff
175 lines
5.0 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "TEE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" tee
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.SH NAME
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tee \- duplicate standard input
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.SH SYNOPSIS
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.LP
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\fBtee\fP \fB[\fP\fB-ai\fP\fB][\fP\fIfile\fP\fB...\fP\fB]\fP
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.SH DESCRIPTION
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.LP
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The \fItee\fP utility shall copy standard input to standard output,
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making a copy in zero or more files. The \fItee\fP utility
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shall not buffer output.
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.LP
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If the \fB-a\fP option is not specified, output files shall be written
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(see \fIFile
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Read, Write, and Creation\fP .
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.SH OPTIONS
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.LP
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The \fItee\fP utility shall conform to the Base Definitions volume
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of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.LP
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The following options shall be supported:
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.TP 7
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\fB-a\fP
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Append the output to the files.
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.TP 7
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\fB-i\fP
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Ignore the SIGINT signal.
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.sp
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.SH OPERANDS
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.LP
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The following operands shall be supported:
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.TP 7
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\fIfile\fP
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A pathname of an output file. Processing of at least 13 \fIfile\fP
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operands shall be supported.
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.sp
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.SH STDIN
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.LP
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The standard input can be of any type.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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The following environment variables shall affect the execution of
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\fItee\fP:
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.TP 7
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\fILANG\fP
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Provide a default value for the internationalization variables that
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are unset or null. (See the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
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for
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the precedence of internationalization variables used to determine
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the values of locale categories.)
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.TP 7
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\fILC_ALL\fP
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If set to a non-empty string value, override the values of all the
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other internationalization variables.
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.TP 7
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\fILC_CTYPE\fP
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Determine the locale for the interpretation of sequences of bytes
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of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).
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.TP 7
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\fILC_MESSAGES\fP
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Determine the locale that should be used to affect the format and
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contents of diagnostic messages written to standard
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error.
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.TP 7
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\fINLSPATH\fP
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Determine the location of message catalogs for the processing of \fILC_MESSAGES
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\&.\fP
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.sp
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default, except that if the \fB-i\fP option was specified, SIGINT
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shall be ignored.
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.SH STDOUT
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.LP
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The standard output shall be a copy of the standard input.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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If any \fIfile\fP operands are specified, the standard input shall
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be copied to each named file.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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The following exit values shall be returned:
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.TP 7
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\ 0
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The standard input was successfully copied to all output files.
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.TP 7
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>0
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An error occurred.
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.sp
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.SH CONSEQUENCES OF ERRORS
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.LP
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If a write to any successfully opened \fIfile\fP operand fails, writes
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to other successfully opened \fIfile\fP operands and
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standard output shall continue, but the exit status shall be non-zero.
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Otherwise, the default actions specified in \fIUtility Description
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Defaults\fP apply.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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The \fItee\fP utility is usually used in a pipeline, to make a copy
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of the output of some utility.
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.LP
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The \fIfile\fP operand is technically optional, but \fItee\fP is no
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more useful than \fIcat\fP when none is specified.
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.SH EXAMPLES
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.LP
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Save an unsorted intermediate form of the data in a pipeline:
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.sp
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.RS
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.nf
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\fB\&... | tee unsorted | sort > sorted
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\fP
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.fi
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.RE
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.SH RATIONALE
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.LP
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The buffering requirement means that \fItee\fP is not allowed to use
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ISO\ C standard fully buffered or line-buffered
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writes. It does not mean that \fItee\fP has to do 1-byte reads followed
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by 1-byte writes.
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.LP
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It should be noted that early versions of BSD ignore any invalid options
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and accept a single \fB'-'\fP as an alternative to
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\fB-i\fP. They also print a message if unable to open a file:
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.sp
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.RS
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.nf
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\fB"tee: cannot access %s\\n", <\fP\fIpathname\fP\fB>
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\fP
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.fi
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.RE
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.LP
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Historical implementations ignore write errors. This is explicitly
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not permitted by this volume of
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IEEE\ Std\ 1003.1-2001.
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.LP
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Some historical implementations use O_APPEND when providing append
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mode; others use the \fIlseek\fP() function to seek to the end-of-file
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after opening the file without O_APPEND. This
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volume of IEEE\ Std\ 1003.1-2001 requires functionality equivalent
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to using O_APPEND; see \fIFile Read, Write, and Creation\fP .
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIIntroduction\fP , \fIcat\fP , the System Interfaces volume of
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IEEE\ Std\ 1003.1-2001, \fIlseek\fP()
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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