The logger 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 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
IEEE Std 1003.1-2001, 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 internationalization variables.
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
Determine the location of message catalogs for the
processing of LC_MESSAGES.
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.
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 IEEE Std 1003.1-2001.
The text with LC_MESSAGES about diagnostic messages means diagnostics
from logger to the user or application, not diagnostic messages that
the user is sending to the system administrator.
Multiple string arguments are allowed, similar to echo, for
Like the utilities mailx and lp, logger is admittedly
difficult to test. This was not deemed sufficient justification to exclude
these utilities from this volume of IEEE Std 1003.1-2001. It is
also arguable that they are, in fact, testable, but that the tests themselves
are not portable.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html