1TEE(1P) POSIX Programmer's Manual TEE(1P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 tee — duplicate standard input
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16 tee [−ai] [file...]
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19 The tee utility shall copy standard input to standard output, making a
20 copy in zero or more files. The tee utility shall not buffer output.
21 If the −a option is not specified, output files shall be written (see
23 Section 1.1.1.4, File Read, Write, and Creation.
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26 The tee utility shall conform to the Base Definitions volume of
27 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
28 The following options shall be supported:
30 −a Append the output to the files.
32 −i Ignore the SIGINT signal.
34
36 The following operands shall be supported:
37 file A pathname of an output file. If a file operand is '−', it
39 shall refer to a file named −; implementations shall not
40 treat it as meaning standard output. Processing of at least
41 13 file operands shall be supported.
42
44 The standard input can be of any type.
45
47 None.
48
50 The following environment variables shall affect the execution of tee:
51 LANG Provide a default value for the internationalization vari‐
53 ables that are unset or null. (See the Base Definitions vol‐
54 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
55 ables for the precedence of internationalization variables
56 used to determine the values of locale categories.)
57 LC_ALL If set to a non-empty string value, override the values of
59 all the other internationalization variables.
60 LC_CTYPE Determine the locale for the interpretation of sequences of
62 bytes of text data as characters (for example, single-byte as
63 opposed to multi-byte characters in arguments).
64 LC_MESSAGES
66 Determine the locale that should be used to affect the format
67 and contents of diagnostic messages written to standard
68 error.
69 NLSPATH Determine the location of message catalogs for the processing
71 of LC_MESSAGES.
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74 Default, except that if the −i option was specified, SIGINT shall be
75 ignored.
76
78 The standard output shall be a copy of the standard input.
79
81 The standard error shall be used only for diagnostic messages.
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84 If any file operands are specified, the standard input shall be copied
85 to each named file.
86
88 None.
89
91 The following exit values shall be returned:
92 0 The standard input was successfully copied to all output files.
94 >0 An error occurred.
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98 If a write to any successfully opened file operand fails, writes to
99 other successfully opened file operands and standard output shall con‐
100 tinue, but the exit status shall be non-zero. Otherwise, the default
101 actions specified in Section 1.4, Utility Description Defaults apply.
102 The following sections are informative.
104
106 The tee utility is usually used in a pipeline, to make a copy of the
107 output of some utility.
108 The file operand is technically optional, but tee is no more useful
110 than cat when none is specified.
111
113 Save an unsorted intermediate form of the data in a pipeline:
114 ... | tee unsorted | sort > sorted
116
118 The buffering requirement means that tee is not allowed to use ISO C
119 standard fully buffered or line-buffered writes. It does not mean that
120 tee has to do 1-byte reads followed by 1-byte writes.
121 It should be noted that early versions of BSD ignore any invalid
123 options and accept a single '−' as an alternative to −i. They also
124 print a message if unable to open a file:
125 "tee: cannot access %s\n", <pathname>
127 Historical implementations ignore write errors. This is explicitly not
129 permitted by this volume of POSIX.1‐2008.
130 Some historical implementations use O_APPEND when providing append
132 mode; others use the lseek() function to seek to the end-of-file after
133 opening the file without O_APPEND. This volume of POSIX.1‐2008 requires
134 functionality equivalent to using O_APPEND; see Section 1.1.1.4, File
135 Read, Write, and Creation.
136
138 None.
139
141 Chapter 1, Introduction, cat
142 The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
144 Variables, Section 12.2, Utility Syntax Guidelines
145 The System Interfaces volume of POSIX.1‐2008, lseek()
147
149 Portions of this text are reprinted and reproduced in electronic form
150 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
151 -- Portable Operating System Interface (POSIX), The Open Group Base
152 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
153 cal and Electronics Engineers, Inc and The Open Group. (This is
154 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
155 event of any discrepancy between this version and the original IEEE and
156 The Open Group Standard, the original IEEE and The Open Group Standard
157 is the referee document. The original Standard can be obtained online
158 at http://www.unix.org/online.html .
159 Any typographical or formatting errors that appear in this page are
161 most likely to have been introduced during the conversion of the source
162 files to man page format. To report such errors, see https://www.ker‐
163 nel.org/doc/man-pages/reporting_bugs.html .
164IEEE/The Open Group 2013 TEE(1P)