LOGGER(1P) POSIX Programmer's Manual LOGGER(1P)PROLOG
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.
NAMElogger - log messages
SYNOPSISlogger string ...
DESCRIPTION
The logger utility saves a message, in an unspecified manner and for‐
mat, containing the string operands provided by the user. The messages
are expected to be evaluated later by personnel performing system
administration tasks.
It is implementation-defined whether messages written in locales other
than the POSIX locale are effective.
OPTIONS
None.
OPERANDS
The following operand shall be supported:
string One of the string arguments whose contents are concatenated
together, in the order specified, separated by single <space>s.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of log‐
ger:
LANG 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 Vari‐
ables for the precedence of internationalization variables used
to determine the values of locale categories.)
LC_ALL If set to a non-empty string value, override the values of all
the other internationalization variables.
LC_CTYPE
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).
LC_MESSAGES
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.)
NLSPATH
Determine the location of message catalogs for the processing of
LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
Not used.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
Unspecified.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
This utility allows logging of information for later use by a system
administrator or programmer in determining why non-interactive utili‐
ties 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.
EXAMPLES
A batch application, running non-interactively, tries to read a config‐
uration file and fails; it may attempt to notify the system administra‐
tor with:
logger myname: unable to read file foo. [timestamp]
RATIONALE
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 configu‐
ration 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 functional‐
ity 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 ease-of-
use.
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.
FUTURE DIRECTIONS
None.
SEE ALSO
lp, mailx, write()COPYRIGHT
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 .
IEEE/The Open Group 2003 LOGGER(1P)
