environ —
user process environment
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:
  - AUDIOCTLDEVICE
- The name of the audio control device to be used by
      audioctl(1),
      audioplay(1) and
      audiorecord(1).
- AUDIODEVICE
- The name of the audio device to be used by
      audioplay(1) and
      audiorecord(1).
- BLOCKSIZE
- The size of the block units used by several commands, most notably
      df(1),
      du(1) and
      ls(1).
      BLOCKSIZEmay be specified in units of a byte by
      specifying a number, in units of a kilobyte by specifying a number
      followed by ‘K’ or
      ‘k’, in units of a megabyte by
      specifying a number followed by ‘M’
      or ‘m’ and in units of a gigabyte by
      specifying a number followed by ‘G’
      or ‘g’. Sizes less than 512 bytes or
      greater than a gigabyte are ignored.
- EDITRC
- Gives the path name of the file used by
      editline(7) when command
      line editing is enabled in various programs. See
      editrc(5) for information on
      the format of the file.
- EXINIT
- A startup list of commands read by
      ex(1) and
      vi(1).
- HOME
- A user's login directory, set by
      login(1) from the password
      file passwd(5).
- LANG
- Default for all NLS categories. Only used if
      LC_ALLor the environment variable for a
      particular NLS category is not provided
      (LC_COLLATE,LC_CTYPE,LC_MESSAGES,LC_MONETARY,LC_NUMERIC, orLC_TIME).
- LC_ALL
- Override for all NLS categories. If set, overrides the values of
      LC_COLLATE,LC_CTYPE,LC_MESSAGES,LC_MONETARY,LC_NUMERIC, andLC_TIME.
- LC_COLLATE
- NLS string-collation order information.
- LC_CTYPE
- NLS character classification, case conversion, and other character
      attributes.
- LC_MESSAGES
- NLS format for affirmative and negative responses.
- LC_MONETARY
- NLS rules and symbols for formatting monetary numeric information.
- LC_NUMERIC
- NLS rules and symbols for formatting nonmonetary numeric information.
- LC_TIME
- NLS rules and symbols for formatting time and date information.
- LIBC_DIAGASSERT
- Control how the _DIAGASSERT() macro (from<assert.h>) behaves once
      the assertion is raised. Refer to
      _DIAGASSERT(3) for more
      information.
- LOGNAME
- The login name of the user.
- MALLOC_OPTIONS
- Control the behaviour of the malloc() function.
      Refer to jemalloc(3) for
      more information.
- MIXERDEVICE
- The name of the audio mixer device to be used by
      mixerctl(1).
- The program used for paginating the output of several commands such as
      man(1). If null or not set, the
      standard pagination program
      more(1) will be used.
- PATH
- The sequence of directories, separated by colons, searched by
      csh(1),
      sh(1),
      system(3),
      execvp(3), etc, when looking
      for an executable file. PATHis set to/usr/bin:/bin:/usr/pkg/bin:/usr/local/bin
 initially by
        login(1). 
- PRINTER
- The name of the default printer to be used by
      lpr(1),
      lpq(1), and
      lprm(1).
- RCMD_CMD
- When using the rcmd(3)
      function, this variable is used as the program to run instead of
      rcmd(1).
- SHELL
- The full pathname of the user's login shell.
- TERM
- The kind of terminal for which output is to be prepared. This information
      is used by commands, such as
      nroff(1) which may exploit
      special terminal capabilities. See
      /usr/share/misc/terminfo
      (terminfo(5)) for a list
      of terminal types.
- TERMCAP
- The string describing the terminal in TERM, or, if
      it begins with a ‘/’, the name of
      the termcap file. This is only checked ifTERMINFOis not set.
- TERMINFO
- The string describing the terminal in TERM, or, if
      it begins with a ‘/’, the name of
      the terminfo file.
- TIMEFORMAT
- A strftime(3) format
      string that may be used by programs such as
      dump(8) for formatting
      timestamps.
- TMPDIR
- The directory in which to store temporary files. Most applications use
      either /tmp or /var/tmp.
      Setting this variable will make them use another directory.
- TZ
- The timezone to use when displaying dates. The normal format is a pathname
      relative to /usr/share/zoneinfo. For example, the
      command
    
    env TZ=US/Pacific
      date
 displays the current time in California. See
        tzset(3) for more
        information. 
- USER
- The login name of the user. It is recommended that portable applications
      use LOGNAMEinstead.
Further names may be placed in the environment by the
    export command and name=value
    arguments in sh(1), or by the
    setenv command if you use
    csh(1). It is unwise to change
    certain sh(1) variables that are
    frequently exported by .profile files, such as
    MAIL, PS1,
    PS2, and IFS, unless you
    know what you are doing.
audioctl(1),
  audioplay(1),
  audiorecord(1),
  csh(1),
  ex(1),
  login(1),
  man(1),
  more(1),
  sh(1),
  execve(2),
  _DIAGASSERT(3),
  execle(3),
  jemalloc(3),
  rcmd(3),
  system(3),
  termcap(3),
  terminfo(3),
  audio(4),
  terminfo(5),
  nls(7),
  dump(8)
The environ manual page appeared in
  4.2BSD.