1TEE(1P) POSIX Programmer's Manual TEE(1P)
2
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
12 tee — duplicate standard input
13
15 tee [-ai] [file...]
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18 The tee utility shall copy standard input to standard output, making a
19 copy in zero or more files. The tee utility shall not buffer output.
20 If the -a option is not specified, output files shall be written (see
22 Section 1.1.1.4, File Read, Write, and Creation.
23
25 The tee utility shall conform to the Base Definitions volume of
26 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
27 The following options shall be supported:
29 -a Append the output to the files.
31 -i Ignore the SIGINT signal.
33
35 The following operands shall be supported:
36 file A pathname of an output file. If a file operand is '-', it
38 shall refer to a file named -; implementations shall not
39 treat it as meaning standard output. Processing of at least
40 13 file operands shall be supported.
41
43 The standard input can be of any type.
44
46 None.
47
49 The following environment variables shall affect the execution of tee:
50 LANG Provide a default value for the internationalization vari‐
52 ables that are unset or null. (See the Base Definitions vol‐
53 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
54 ables for the precedence of internationalization variables
55 used to determine the values of locale categories.)
56 LC_ALL If set to a non-empty string value, override the values of
58 all the other internationalization variables.
59 LC_CTYPE Determine the locale for the interpretation of sequences of
61 bytes of text data as characters (for example, single-byte as
62 opposed to multi-byte characters in arguments).
63 LC_MESSAGES
65 Determine the locale that should be used to affect the format
66 and contents of diagnostic messages written to standard
67 error.
68 NLSPATH Determine the location of message catalogs for the processing
70 of LC_MESSAGES.
71
73 Default, except that if the -i option was specified, SIGINT shall be
74 ignored.
75
77 The standard output shall be a copy of the standard input.
78
80 The standard error shall be used only for diagnostic messages.
81
83 If any file operands are specified, the standard input shall be copied
84 to each named file.
85
87 None.
88
90 The following exit values shall be returned:
91 0 The standard input was successfully copied to all output files.
93 >0 An error occurred.
95
97 If a write to any successfully opened file operand fails, writes to
98 other successfully opened file operands and standard output shall con‐
99 tinue, but the exit status shall be non-zero. Otherwise, the default
100 actions specified in Section 1.4, Utility Description Defaults apply.
101 The following sections are informative.
103
105 The tee utility is usually used in a pipeline, to make a copy of the
106 output of some utility.
107 The file operand is technically optional, but tee is no more useful
109 than cat when none is specified.
110
112 Save an unsorted intermediate form of the data in a pipeline:
113 ... | 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>
128 Historical implementations ignore write errors. This is explicitly not
130 permitted by this volume of POSIX.1‐2017.
131 Some historical implementations use O_APPEND when providing append
133 mode; others use the lseek() function to seek to the end-of-file after
134 opening the file without O_APPEND. This volume of POSIX.1‐2017 requires
135 functionality equivalent to using O_APPEND; see Section 1.1.1.4, File
136 Read, Write, and Creation.
137
139 None.
140
142 Chapter 1, Introduction, cat
143 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
145 Variables, Section 12.2, Utility Syntax Guidelines
146 The System Interfaces volume of POSIX.1‐2017, lseek()
148
150 Portions of this text are reprinted and reproduced in electronic form
151 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
152 table Operating System Interface (POSIX), The Open Group Base Specifi‐
153 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
154 Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/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 2017 TEE(1P)