# logger

## 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.
    


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