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A crude, simple means of InterProcessCommunication, often used for trivial configuration needs.

AddToMe: inherited by child processes, cannot be changed at runtime from outside process, etc.

Invoke [printenv(1)] to print a list of the current values of all the [EnvironmentVariable]s in the invoking process.

Since [make(1)] often uses [EnvironmentVariable]s named after commands to store the path to command in question, such names should be avoided for other purposes. Examples include <tt>CC</tt>, <tt>BISON</tt>, <tt>YACC</tt>, <tt>LEX</tt>, <tt>FLEX</tt>, <tt>F77</tt>, <tt>LD</tt> etc. It also uses the <tt>FLAGS</tt> suffix for default flags to pass a command, eg: <tt>CFLAGS</tt>, <tt>LDFLAGS</tt>, etc.

----

!! A list of environment variables consulted by commonly used programs, libraries etc

''No claims as to comprehensiveness or correctness made.''

<tt>APT_CONFIG</tt>:
    see [apt.conf(5)]
<tt>ASPELL_CONF</tt>:
    Configuration file for aspell, see [aspell(1)]
<tt>BROWSER</tt>:
    The user's prefered browser (see [The BROWSER project | http:/catb.org/~esr/BROWSER/])
<tt>BZCAT</tt>:
    Command line arguments for bzcat
<tt>BZIP2</tt>:
    Command line arguments for BZIP2
<tt>COLUMNS</tt>:
    Number of columns on the screen
<tt>DEAD</tt>:
    used by [Mail(1)] apparently.
<tt>DISPLAY</tt>:
    Current [X(1)] display
<tt>EDITOR</tt>:
    Users prefered program to edit text files
<tt>ftp_proxy</tt>:
    ftp proxy server, used by various programs (eg see [apt.conf(5)], [lynx(1)], [wget(1)], ...)
<tt>HOME</tt>:
    Home directory
<tt>HOSTALIASES</tt>:
    Path to host aliases file, see [hostname(7)].
<tt>HOSTFILE</tt>:
    Path to <tt>/etc/hosts</tt>
<tt>http_proxy</tt>:
    http proxy server, used by various programs (eg see [apt.conf(5)], [lynx(1)], [wget(1)], ...)
<tt>[HZ]</tt>:
    Kernel timer mechanism
<tt>IFS</tt>:
    Internal Field Seperator, used for word splitting in shells, see [bash(1)]
<tt>INPUTRC</tt>:
    Path to .inputrc file.  see [bash(1)]
<tt>LANG</tt>:
    The name of the locale to use for locale categories.  See [locale(5)]
<tt>LC_ADDRESS</tt>:
    Locale settings, see [locale(1)]
<tt>LC_ALL</tt>:
    Locale settings, see [locale(1)]
<tt>LC_COLLATE</tt>:
    Locale settings, see [locale(1)]
<tt>LC_CTYPE</tt>:
    Locale settings, see [locale(1)]
<tt>LC_IDENTIFICATION</tt>:
    Locale settings, see [locale(1)]
<tt>LC_MEASUREMENT</tt>:
    Locale settings, see [locale(1)]
<tt>LC_MESSAGES</tt>:
    Locale settings, see [locale(1)]
<tt>LC_MONETARY</tt>:
    Locale settings, see [locale(1)]
<tt>LC_NAME</tt>:
    Locale settings, see [locale(1)]
<tt>LC_NUMERIC</tt>:
    Locale settings, see [locale(1)]
<tt>LC_PAPER</tt>:
    Locale Paper size, see [locale(1)]
<tt>LC_TELEPHONE</tt>:
    Locale settings, see [locale(1)]
<tt>LD_AOUT_LIBRARY_PATH</tt>:
    LD_LIBRARY_PATH for a.out binaries
<tt>LD_AOUT_PRELOAD</tt>:
    LD_PRELOAD for a.out binaries
<tt>LD_ASSUME_KERNEL</tt>:
    used to control the choice of threading implementation by [pthreads(7)], and [other things as well|http://people.redhat.com/drepper/assumekernel.html].
<tt>LD_BIND_NOW</tt>:
    Disable lazy linking, see [ld.so(8)]
<tt>LD_KEEPDIR</tt>:
    Don't ignore directory names of a.out libraries.  see [ld.so(8)]
<tt>LD_LIBRARY_PATH</tt>:
    Path to search for libraries, see [ld.so(8)]
<tt>LD_NOWARN</tt> :
    Suppress warnings of a.out minor version differences, see [ld.so(8)]
<tt>LD_PRELOAD</tt>:
    Libraries to load before all others, see [ld.so(8)]
<tt>LD_TRACE_LOADED_OBJECTS</tt>:
    Give ldd output instead of running, see [ld.so(8)]
<tt>LESSANSIENDCHARS</tt>:
    see [less(1)]
<tt>LESSBINFMT</tt>:
    see [less(1)]
<tt>LESSCHARDEF</tt>:
    Charset definition for [less(1)]
<tt>LESSCHARSET</tt>:
    Charset used by [less(1)] to display.
<tt>LESSCLOSE</tt>:
    see [less(1)]
<tt>LESSECHO</tt>:
    see [less(1)]
<tt>LESSEDIT</tt>:
    Editor used by [less(1)]
<tt>LESSGLOBALTAGS</tt>:
    see [less(1)]
<tt>LESSKEY</tt>:
    Name of the [lesskey(1)] file
<tt>LESSKEY_SYSTEM</tt>:
    Name of the system wide [lesskey(1)] file
<tt>LESSMETAESCAPE</tt>:
    see [less(1)]
<tt>LESSOPEN</tt>:
    [less(1)] preprocessor
<tt>LESS</tt>:
    options passed to [less(1)] automatically
<tt>LESSSECURE</tt>:
    Put [less(1)] into secure mode.
<tt>LESSSEPERATOR</tt>:
    used by [less(1)]
<tt>LINES</tt>:
    Number of lines on the screen
<tt>LISTER</tt>:
    Used by [Mail(1)], obsolete version of <tt>PAGER</tt>?
<tt>LOCALDOMAIN</tt>:
    Local domain, see [hostname(7)]
<tt>LOGNAME</tt>:
    The name of the logged in user
<tt>LPDEST</tt>:
    Default printer
<tt>MAILCHECK</tt>:
    How often to check for mail (in seconds), see [bash(1)]
<tt>MAIL</tt>:
    File for the shell to check for mail, see [bash(1)]
<tt>MAILPATH</tt>:
    Files for the shell to check for mail, see [bash(1)]
<tt>[MALLOC_CHECK_]</tt>:
    Change the implementation of [malloc(3)] to catch more bugs.
<tt>MANPATH</tt>:
    Path to search for man pages
<tt>MBOX</tt>:
    Path to mbox file? see [Mail(1)]
<tt>NGPRNTER</tt>:
    Default printer, see [lpr(1)]
<tt>NPRINTER</tt>:
    Default printer, see [lpr(1)]
<tt>PAGER</tt>:
    The user's prefered pager program
<tt>PATH</tt>:
    Path to search for programs
<tt>[POSIXLY_CORRECT]</tt>:
    Makes programs/libraries adhere to strict [POSIX] requirements.
<tt>PRINTER</tt>:
    Default printer
<tt>PROMPT_COMMAND</tt>:
    Command for the shell to run every time it displays a prompt, see [bash(1)]
<tt>PS1</tt>:
    Shell prompt; see [bash(1)], particularly the __PROMPTING__ section for info on how to change the shell prompt.
    <br><tt>PS1='\e[31m\A\e[0m \u@\h:\w>'</tt> looks quite nice :)
<tt>PS2</tt>:
    Secondary Shell prompt, displayed when a previous line continues; see [bash(1)]. (You will see this prompt if you forget to close a quote.)
<tt>PS3</tt>:
    Shell prompt, see [bash(1)]
<tt>PS4</tt>:
    Shell prompt, see [bash(1)]
<tt>PWD</tt>:
    Process Working Directory (set by some shells)
<tt>REPLYTO</tt>:
    Used by [Mail(1)], reply to address?
<tt>RESOLV_ADD_TRIM_DOMAINS</tt>:
    Adds to Trim Domains, see [resolv+(8)]
<tt>RESOLV_HOST_CONF</tt>:
    Filename of <tt>/etc/host.conf</tt>.  see [resolv+(8)], [host.conf(5)]
<tt>RESOLV_MULTI</tt>:
    Overrides "multi" keyword from <tt>/etc/host.conf</tt>, see [resolv+(8)]
<tt>RESOLV_OVERRIDE_TRIM_DOMAINS</tt>:
    Overrides Tirm Domains from <tt>/etc/host.conf</tt>, see [resolv+(8)]
<tt>RESOLV_REORDER</tt>:
    Overrides the "reorder" keyword from <tt>/etc/host.conf</tt>, see [resolv+(8)]
<tt>RESOLV_SERV_ORDER</tt>:
    Overrides "order" keyword in <tt>/etc/host.conf</tt>, see [resolv+(8)]
<tt>RESOLV_SPOOF_CHECK</tt>:
    Sets Spoof Checking see [resolv+(8)]
<tt>SHELL</tt>:
    The user's shell
<tt>SSH_ASKPASS</tt>:
    Used by [ssh(1)]
<tt>SSH_AUTH_SOCK</tt>:
    Used by [ssh(1)]
<tt>SSH_CLIENT</tt>:
    Used by [ssh(1)]
<tt>SSH_ORIGINAL_COMMAND</tt>:
    Used by [ssh(1)]
<tt>SSH_TTY</tt>:
    Used by [ssh(1)]
<tt>SYSTEM</tt>:
    Operating System, used by [apropos(1)]
<tt>TERMCAP</tt>:
    Terminal type capabilities file
<tt>TERM</tt>:
    The terminal type
<tt>TIMEFORMAT</tt>:
    format of the [time(1)] command, see [time(1)] and [bash(1)]
<tt>TMOUT</tt>:
    Timeout for shells to log you out, see [bash(1)]
<tt>TMPDIR</tt>:
    Directory for temp files, see [tempnam(3)], [sort(1)] etc  See PerUserTempDirs
<tt>TZDIR</tt>:
    Set TimeZone information
<tt>TZ</tt>:
    Set TimeZone information, [tzset(1)]
<tt>USER</tt>:
    The currently logged in user
<tt>VISUAL</tt>:
    The user's prefered visual editor
Last edited on Friday, September 26, 2008 10:14:07 pm by LawrenceDoliveiro
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