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LOGNAME (str)

Username for the current session (historic)

Description

LOGNAME returns the user name of the current Murex session. It’s behaviour is identical to USER.

LOGNAME is a historical relic. Please use USER in your scripts instead.

This is a reserved variable so it cannot be changed.

Detail

USER vs LOGNAME

The $USER and $LOGNAME environment variables serve similar but slightly different purposes. Plus and their distinctions stem from historical and compatibility reasons.

1. Historical Context:
   • $LOGNAME originates from early AT&T UNIX systems and was intended to hold the user’s login name, particularly for system utilities that relied on it.

     It has been part of POSIX since early UNIX specifications, which is why it is a required variable in POSIX-compliant systems.

   • $USER came from BSD UNIX and was commonly used by shells and more user- focused applications. This variable has been adopted widely in modern systems like Linux to refer to the current user within shell scripts and interactive environments.
2. Functional Difference:

   Both variables typically hold the same value, representing the current user’s login name. However, in certain contexts in POSIX environments, (such as running sudo from Bash), their behavior may differ:

   • $LOGNAME is more tightly bound to the user who originally logged in,
   • while $USER may be altered during a session.

   With regards to Murex, both variables call the same underlying function and thus will always return the same values under all circumstances.

3. Why Two Variables?:
   • In POSIX shells like Bash, the existence of both $LOGNAME and $USER reflects the integration of features from both AT&T UNIX and BSD UNIX. Although they usually return the same value, POSIX mandates $LOGNAME for broader system compatibility, especially with utilities that depend on login information.
   • However with Murex, there isn’t any requirement to maintain POSIX compatibility with AT&T UNIX. What’s more, neither of these two variables are defined as environmental variables.

     The reason Murex retains supports for $LOGNAME as a reserved variable is simply to ensure nobody accidentally uses $LOGNAME for any other purposes (such as logging) and then get confused why other utilities might break after they’ve overwritten the contents of $LOGNAME

See Also

• Reserved Variables: Special variables reserved by Murex
• USER (str): Username for the current session
• str (string): string (primitive)

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This document was generated from gen/variables/LOGNAME_doc.yaml.