This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding Linux
manual page for details of Linux behavior), or the interface may not be
implemented on Linux.
logger — log messages
utility saves a message, in an unspecified manner and format,
containing the string
operands provided by the user. The messages are
expected to be evaluated later by personnel performing system administration
It is implementation-defined whether messages written in locales other than the
POSIX locale are effective.
The following operand shall be supported:
- One of the string arguments whose contents are concatenated together, in
the order specified, separated by single <space> characters.
The following environment variables shall affect the execution of logger
- Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1‐2008,
Section 8.2, Internationalization Variables for the
precedence of internationalization variables used to determine the values
of locale categories.)
- If set to a non-empty string value, override the values of all the other
- Determine the locale for the interpretation of sequences of bytes of text
data as characters (for example, single-byte as opposed to multi-byte
characters in arguments).
Determine the locale that should be used to affect the format and contents
of diagnostic messages written to standard error. (This means diagnostics
from logger to the user or application, not diagnostic messages
that the user is sending to the system administrator.)
- Determine the location of message catalogs for the processing of
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
- Successful completion.
- An error occurred.
The following sections are informative.
This utility allows logging of information for later use by a system
administrator or programmer in determining why non-interactive utilities have
failed. The locations of the saved messages, their format, and retention
period are all unspecified. There is no method for a conforming application to
read messages, once written.
A batch application, running non-interactively, tries to read a configuration
file and fails; it may attempt to notify the system administrator with:
logger myname: unable to read file foo. [timestamp]
The standard developers believed strongly that some method of alerting
administrators to errors was necessary. The obvious example is a batch
utility, running non-interactively, that is unable to read its configuration
files or that is unable to create or write its results file. However, the
standard developers did not wish to define the format or delivery mechanisms
as they have historically been (and will probably continue to be) very
system-specific, as well as involving functionality clearly outside the scope
of this volume of POSIX.1‐2008.
The text with LC_MESSAGES
about diagnostic messages means diagnostics
to the user or application, not diagnostic messages that
the user is sending to the system administrator.
arguments are allowed, similar to echo
Like the utilities mailx
difficult to test. This was not deemed sufficient justification to exclude
these utilities from this volume of POSIX.1‐2008. It is also arguable
that they are, in fact, testable, but that the tests themselves are not
The Base Definitions volume of POSIX.1‐2008, Chapter 8
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
7, Copyright (C) 2013 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013
Technical Corrigendum 1 applied.) In the event of any discrepancy between this
version and the original IEEE and The Open Group Standard, the original IEEE
and The Open Group Standard is the referee document. The original Standard can
be obtained online at http://www.unix.org/online.html .
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