logger(1p) — Linux manual page
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.
NAME
logger — log messages
SYNOPSIS
logger string...
DESCRIPTION
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 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> characters.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of
logger:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables 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 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.
EXAMPLES
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]
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 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.1‐2017.
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 POSIX.1‐2017. It is also
arguable that they are, in fact, testable, but that the tests
themselves are not portable.
FUTURE DIRECTIONS
None.
SEE ALSO
lp(1p), mailx(1p), write(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .