ENVIRON(7)						 Miscellaneous Information Manual						ENVIRON(7)

NAME

       environ - user environment

SYNOPSIS

       extern char *const *environ;

DESCRIPTION

       An  array  of  strings called the `environment' is made available by execve(2) when a process begins.  By convention these strings have the
       form `name=value'.  The following names are used by various commands:

       PATH    The sequence of directory prefixes that sh, time, nice(1), etc., apply in searching for a file known by an  incomplete  path  name.
	       The  prefixes  are  separated by `:'.  Login shells set PATH=:/bin:/usr/bin.  Note that the empty space between the `=' and the `:'
	       indicates the current directory.  Security aware people move the extra `:' to the end of their path or omit it.

       HOME    A user's login directory, set by login(1) from the password file passwd(5).

       TERM    The kind of terminal for which output is to be prepared.  This information is used by programs that wish to exploit special  termi-
	       nal  capabilities,  a  screen  oriented	text  editor  for  instance.   The  terminal type is set by login(1) from the tty database
	       ttytab(5).

       SHELL   The file name of the users login shell, set by login(1) from the password file passwd(5).

       TERMCAP The string describing the terminal in TERM, or the name of the termcap file, see termcap(5), termcap(3).

       EXINIT  A startup list of commands read by elvis(1).

       USER    The login name of the user, set by login(1) from the password file passwd(5).

       LOGNAME Set to the same value as USER.  BSD derived systems have USER, System V has LOGNAME, so modern systems have both to avoid problems.

	      Further names may be placed in the environment by the
	      export command and `name=value' arguments in sh(1).  Arguments may also be placed in their  environment  by  programs  if  they  use
	      putenv(3).   Or  in  the	environment of another program by building a new environment for one of the exec functions that accepts an
	      environment list, like execle(2) or execve(2).  It is unwise to conflict with certain sh(1) variables that are frequently set and/or
	      exported by `.profile' files: MAIL, PS1, PS2, IFS.

SEE ALSO

       elvis(1), login(1), sh(1), execl(2), execve(2), system(3), termcap(3), termcap(5), ttytab(5).

4.2 Berkeley Distribution					   May 20, 1985 							ENVIRON(7)