Appendix: Commonly Used Environment Variables

This appendix describes most of the environment variables that are commonly used under QNX Neutrino.

Use these links to locate an entry quickly:

A ¦ B ¦ C ¦ D ¦ E ¦ F ¦ G ¦ H ¦ I ¦ J ¦ L ¦ M ¦ N ¦ O ¦ P ¦ Q ¦ R ¦ S ¦ T ¦ U

For general information about setting environment variables, see the Configuring Your Environment chapter of the Neutrino User's Guide; for specific information, see the related utilities and programs.

A

ABLANG: A language code (e.g. en_CA for Canadian English) that a multilingual Photon application uses to determine what language to display.
For more information, see the International Language Support chapter of the Photon Programmer's Guide; for the currently supported codes, see /usr/photon/appbuilder/languages.def.
ABLPATH: A list of directories where you want a multilingual Photon application to search for translation files.
For more information, see the International Language Support chapter of the Photon Programmer's Guide, and ph in the Utilities Reference.
AB_RESOVRD: A path variable that lists directories to search for resource records for applications built with PhAB. See the Photon in Embedded Systems appendix of the Photon Programmer's Guide.
ACCEPT_LANGUAGE: Slinger sets this environment variable, for use by CGI scripts. It indicates the languages that can be read by the remote client.
For more information, see slinger in the Utilities Reference.
AUTOCONNECT: In order for the /etc/autoconnect to be run, this environment variable must be defined and set to 1.
For more information, see /etc/autoconnect in the Utilities Reference.

B

BROADCAST: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the client broadcast address that was obtained from the server.

C

CMD_INT: Slinger uses this environment variable to determine the pathname or name of the shell program used to interpret the string passed to the SSI command, exec cmd.
For more information, see slinger in the Utilities Reference.
COLUMNS: The number of character columns on the screen.
CONTENT_LENGTH: Slinger sets this environment variable, for use by CGI scripts. It indicates the length of the attached information in the case of a POST.
For more information, see slinger in the Utilities Reference.
CONTENT_TYPE: Slinger sets this environment variable, for use by CGI scripts. It indicates the type of the attached information in the case of a POST.
For more information, see slinger in the Utilities Reference.

D

DISPLAY

The name of the physical display on which to draw.

DL_DEBUG

If this environment variable is set, the shared library loader displays debugging information about the libraries as they're opened. The value can be a comma-separated list of the following:

all — display all debug messages.
help — display a help message, and then exit.
reloc — display relocation processing messages.
libs — display information about shared objects being opened.
statistics — display runtime linker statistics.
lazyload — print lazy-load debug messages.
debug — print various runtime linker debug messages.

A value of 1 (one) is the same as all.

DOCUMENT_ROOT

Slinger sets this environment variable, for use by CGI scripts. It indicates the location of data files. (Same as HTTPD_ROOT_DIR.)

For more information, see slinger in the Utilities Reference.

DONT_USE_LINK_UNLINK

Indicates to lpr to use rename() instead of link() or unlink().

E

EDITOR: The path of the editor you'd like to use by default.
EXINIT: Default elvis option settings. If set, the contents of this environment variable are executed on startup as a series of ex commands.

F

FILENAME: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the filename supplied in the server response.
FORWARDED: Slinger sets this environment variable, for use by CGI scripts. It indicates the name of the proxy server through which the web page is being processed.
For more information, see slinger in the Utilities Reference.
FROM: Slinger sets this environment variable, for use by CGI scripts. It indicates the name of the remote client user.
For more information, see slinger in the Utilities Reference.

G

GATEWAY: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the gateway that the client is to use.
GATEWAY_INTERFACE: Slinger sets this environment variable, for use by CGI scripts. It indicates the name and version of the Common Gateway Interface served on Slinger.
For more information, see slinger in the Utilities Reference.
GNUTARGET: Specifies the target (output file format) for GNU utilities. For more information, see the Selecting the Target System appendix of the Utilities Reference.
GZIP: A set of default options for gzip

H

HOME: Your current working directory when you first log in. It's specified as one of the fields for each user in /etc/passwd. For more information, see passwd in the Utilities Reference.
HOSTALIASES: The name of a file containing aliases for hosts. For more information, see gethostbyname() in the Library Reference.
HOSTNAME: The name of the host machine.
HTTPD_ROOT_DIR: The name of the directory where Slinger looks for data files. The default is /usr/local/httpd.
For more information, see slinger in the Utilities Reference.
HTTPD_ROOT_DOC: The name of the root document (e.g. index.html) in Slinger.
For more information, see slinger in the Utilities Reference.
HTTPD_SCRIPTALIAS: The directory where Slinger looks for the CGI executables.
For more information, see slinger in the Utilities Reference.
HTTP_ACCEPT: Slinger sets this environment variable, for use by CGI scripts. It indicates the MIME types that the client accepts, as given by HTTP headers.
For more information, see slinger in the Utilities Reference.
HTTP_USER_AGENT: Slinger sets this environment variable, for use by CGI scripts. It indicates the browser that the client is using to send requests.
For more information, see slinger in the Utilities Reference.

I

INTERFACE: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the interface that was configured (e.g. en0).
IOPORT: The pccard-launch utility sets this environment variable to indicate the hex address of the I/O port (e.g. 320).
IOPORT2: The pccard-launch utility sets this environment variable to indicate the hex address of the second I/O port, if assigned.
IOPORT2SZ: The pccard-launch utility sets this environment variable to indicate the size of the second I/O port, if assigned.
IOPORTSZ: The pccard-launch utility sets this environment variable to indicate the size of the I/O port (e.g. 32).
IPADDRESS: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the client IP address that was obtained from the server.
IRQ: The pccard-launch utility sets this environment variable to indicate the IRQ of the device.
IVE_HOME: Used by Java VM.

J

J9PLUGIN_ARGS: Arguments passed to Browser Java plugins.

L

LANG

The locale to use for the locale categories.

QNX Neutrino currently supports only the POSIX (i.e. C) locale.

LC_TYPE

The locale for character classification, used by uniq to determine the characters constituting a blank in the current locale.

QNX Neutrino currently supports only the POSIX (i.e. C) locale.

LDEMULATION

Specifies the linker emulation. For more information, see the Selecting the Target System appendix of the Utilities Reference.

LD_BIND_NOW

Affects lazy-load dependencies due to full symbol resolution. Typically, it forces the loading of all lazy-load dependencies (until all symbols have been resolved).

LD_DEBUG

A synonym for DL_DEBUG. If you set both DL_DEBUG and LD_DEBUG, then DL_DEBUG takes precedence.

LD_DEBUG_OUTPUT

The name of a file in which the dynamic linker writes its output. By default, output is written to stderr.

LD_LIBRARY_PATH

A path to search for shared libraries for a native linker. For more information, see ld in the Utilities Reference

LD_PRELOAD

A list of full paths to the shared libraries on an ELF system that you want to load before loading other libraries. Use a colon (:) to separate the libraries in this list. You can use this environment variable to add or change functionality when you run a program. For setuid or setgid ELF binaries, only libraries in the standard search directories that are also setuid will be loaded. See ld in the Utilities Reference, and dlopen() in the QNX Neutrino Library Reference.

LD_RUN_PATH

A path to search for shared libraries on an ELF system. For more information, see ld in the Utilities Reference

LEASEEXPIRES

The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the time at which the lease expires.

LEASEOBTAINED

The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the time at which the lease was obtained.

LESS

Options that you want to pass to less automatically.

LESSEDIT

The editor prototype string (used for the v command in less).

LINES

The number of character lines on the screen.

LOCALDOMAIN

The local domain name. For more information, see res_init() in the Library Reference.

LOGNAME

The userid you used to login; the same as USERNAME.

M

MAKEFLAGS

A set of default options for make.

MALLOC_OPTIONS

Controls how calloc(), malloc(), and realloc() behave if you specify a size of 0 (or a value of 0 for the n argument to calloc()). The V (“System V”) and R (“use the realloc() behavior of QNX Neutrino 6.4.0 and earlier”) columns below indicate how the functions behave if the value of MALLOC_OPTIONS includes that letter:

Function	Default	`V`	`R`
calloc(n, 0)	Non-NULL	NULL	No effect
malloc(0)	Non-NULL	NULL	No effect
realloc(NULL, 0)	Non-NULL	NULL	No effect
realloc(non-NULL, 0)	Non-NULL	NULL	NULL

In all the above cases, if the function returns a non-NULL pointer, it's valid only for a corresponding call to free() or realloc().

MIBFILE

The location of the mib.txt file.

MKIFS_PATH

A colon-separated list of directories that mkifs should use to search for host files to be included in an OS image.

MORE

Default options for more

N

NAMESERVER1, NAMESERVER2: The dhcp.client passes these environment variables to the /etc/dhcp/dhcp-up script. They indicate the nameservers that the client is to use.
NAME_MAX: The maximum permitted length of a component of a pathname.
NETMASK: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the client netmask that was obtained from the server.

O

OPTIONx: The dhcp.client passes these additional environment variables (where x is the option number) to the /etc/dhcp/dhcp-up script.

P

PATH

A colon-separated list of directories that are searched when the shell looks for commands and .'d files. An empty string resulting from a leading or trailing colon, or two adjacent colons is treated as a ., the current directory.

For more information, see ksh in the Utilities Reference.

PATH_INFO

Slinger sets this environment variable, for use by CGI scripts. It indicates extra path information sent.

For more information, see slinger in the Utilities Reference.

PATH_MAX

The maximum permitted length of a pathname.

PATH_TRANSLATED

Slinger sets this environment variable, for use by CGI scripts. It's the same as the PATH_INFO appended to the pathname in HTTPD_ROOT_DIR.

For more information, see slinger in the Utilities Reference.

PHEXIT_DISABLE

Set this environment variable to turn off the Photon Login dialog's Exit button so that users won't be able to exit to text mode.

For more information, see phlogin in the Utilities Reference.

PHFONT

The registered name of the font server (e.g. /dev/phfont).

For more information, see ph in the Utilities Reference.

PHFONT_USE_EXTERNAL

If this environment variable exists, io-graphics runs the font manager as a separate process (see phfont) instead of using phfont.so. You should set this environment variable for systems that have remote clients accessing font services on the host machine (e.g. phindows, phditto).

PHFONTMEM

The size of an area in shared memory to set up between the task and the Photon font server for returning text bitmaps (normally required only by graphics drivers). For more information, see PfAttach() in the Photon Library Reference.

PHFONTOPTS

Options to pass to the Photon font server. For more information, see phfont.

PHGFX

The full command that you want the ph script to use instead of the default commands to start the graphics driver.

PHINPUT

The full command that you want the ph script to use instead of the default commands to start the input driver.

PHINSTANCE

The number of times that Photon has been instantiated. For more information, see phlogin in the Utilities Reference.

PHOTON

The name of the Photon device (usually /dev/photon). For more information, see ph in the Utilities Reference.

PHOTONOPTS

(Windows-hosted version only) Additional options you want to pass to the Photon server when it starts.

PHOTON_PATH

The name of the root directory containing Photon files (usually /usr/photon). For more information, see ph in the Utilities Reference.

PHOTON2_PATH

Internal use only.

PHSTART

Internal use only.

PHTK_PATH

Internal use only.

PHWM

The name of the Window Manager to start when you start Photon. For more information, see ph in the Utilities Reference.

PHWMEXIT

If you set this environment variable, Photon disables the confirmation dialog when you exit Photon. For more information, see pwm in the Utilities Reference.

PHWMOPTS

Options you want to pass to the window manager when it starts. For more information, see pwm in the Utilities Reference.

POSIX_STRICT

If this environment variable is set, some QNX 4 and QNX Neutrino utilities (e.g. cp, ls, and more) interpret options according to POSIX specifications.

POSIXLY_CORRECT

This environment variable is used by Unix-style operating systems to alter behavior to comply with POSIX where it's different from the OS's default behavior. POSIXLY_CORRECT is a de facto standard that isn't defined by POSIX.

Here are some of its effects:

If the POSIXLY_CORRECT environment variable is set, functions that check the length of a pathname do so before removing any redundant . and .. components. If POSIXLY_CORRECT isn't set, the functions check the length after removing any redundant components.
If the POSIXLY_CORRECT environment variable is set, the posix option to be enabled for ksh. For more information, see “POSIX mode” in the documentation for ksh.

PRINTER

The name of the default printer, used by lpr.

PROCESSOR

Specifies the target CPU when building an image filesystem. If not set, the default is the same as the CPU of the host system (e.g. x86). For more information, see mkifs in the Utilities Reference.

PTERMPAL

The pathname of the palette file for pterm.

PTERMRC

The name of a local configuration file for pterm.

PWMOPTS

(Windows-hosted version only) Options you want to pass to the window manager when it starts. For more information, see pwm in the Utilities Reference.

PWM_PRINTSCRN_APP

The application to start when the Print Scrn key is pressed. The default is snapshot.

PYTHONCASEOK

Ignore case in Python import statements (Windows).

PYTHONDEBUG

Display debugging output from the python parser.

PYTHONHOME

An alternate prefix directory (or prefix:exec_prefix) for Python. The default module search path uses prefix/pythonX.X.

PYTHONINSPECT

Inspect interactively after running the Python script, and force prompts, even if stdin doesn't appear to be a terminal.

PYTHONOPTIMIZE

Optimize the generated Python byte code.

PYTHONPATH

A colon-separated list of directories prefixed to the default module search path for Python. The result is stored in sys.path.

PYTHONSTARTUP

The file to execute on interactive startup of Python (no default).

PYTHONUNBUFFERED

Use unbuffered binary for stdout and stderr. See the Python documentation for details on internal buffering.

PYTHONVERBOSE

Make Python be verbose (trace import statements).

Q

QCC_CONF_PATH: The name of the directory that contains the configuration files for qcc.
QNX_HELP_PATH: The location of the top-level QNX help. This environment variable is used by helpviewer to locate help topics.
QNX_HELP_HOME_PAGE: The location of the “home page” for helpviewer.
QNX_HOST: The location of host-specific files for all development hosts.
QNX_TARGET: The location of target backends on the host machine.
QUERY_STRING: Slinger sets this environment variable, for use by CGI scripts. It indicates the raw query string sent from the remote client.
For more information, see slinger in the Utilities Reference.

R

REFERER: Slinger sets this environment variable, for use by CGI scripts. It indicates the URL of the HTML page that referred the remote client to this web page.
For more information, see slinger in the Utilities Reference.
REMOTE_ADDR: Slinger sets this environment variable, for use by CGI scripts. It indicates the IP address of the remote client.
For more information, see slinger in the Utilities Reference.
REMOTE_HOST: Slinger sets this environment variable, for use by CGI scripts. It indicates the hostname of the remote client.
For more information, see slinger in the Utilities Reference.
REMOTE_IDENT: Slinger sets this environment variable, for use by CGI scripts. It indicates the remote user name if supporting RFC 931 identification.
For more information, see slinger in the Utilities Reference.
REMOTE_PORT: Slinger sets this environment variable, for use by CGI scripts. It indicates the port of the remote client.
For more information, see slinger in the Utilities Reference.
REMOTE_USER: Slinger sets this environment variable, for use by CGI scripts. It indicates the user name used to validate authentication from the remote client.
For more information, see slinger in the Utilities Reference.
REQUEST_METHOD: Slinger sets this environment variable, for use by CGI scripts. It indicates the method by which the current web page was requested (GET or POST).
For more information, see slinger in the Utilities Reference.
RESCONF: An way of overriding configuration strings in the resolv.conf file.

S

SCRIPT_NAME: Slinger sets this environment variable, for use by CGI scripts. It indicates the name of the script being executed.
For more information, see slinger in the Utilities Reference.
SERVER: The dhcp.client passes this environment variable to the /etc/dhcp/dhcp-up script. It indicates the server's IP address.
SERVER_ADMIN: Slinger sets this environment variable, for use by CGI scripts. It indicates the contact information of the administrator of Slinger specified by Slinger's -a option.
For more information, see slinger in the Utilities Reference.
SERVER_NAME: Slinger sets this environment variable, for use by CGI scripts. It indicates the name of the computer where Slinger is running.
For more information, see slinger in the Utilities Reference.
SERVER_PORT: Slinger sets this environment variable, for use by CGI scripts. It indicates the IP port that Slinger is answering on.
For more information, see slinger in the Utilities Reference.
SERVER_PROTOCOL: Slinger sets this environment variable, for use by CGI scripts. It indicates the name and version of HTTP served on Slinger.
For more information, see slinger in the Utilities Reference.
SERVER_ROOT: Slinger sets this environment variable, for use by CGI scripts. It indicates Slinger's current working directory.
For more information, see slinger in the Utilities Reference.
SERVER_SOFTWARE: Slinger sets this environment variable, for use by CGI scripts. It indicates the name of the Slinger software.
For more information, see slinger in the Utilities Reference.
SHELL: The pathname of the command interpreter, or shell, that you want to use. It's set by login.
SMICINCL: A list of directories to search for MIB modules. For more information, see smic in the Utilities Reference.
SNMPCONFIGFILE: The pathname of the snmpd.conf file.
SOCKET: The pccard-launch utility sets this environment variable to indicate the socket where the card is inserted.
SOCKS_NS: The IP address of the domain nameserver that should be used for name resolution by SOCKS client programs.
SOCKS_SERVER: The name or IP address of the SOCKS proxy server host to use, overriding the default server for SOCKS client programs.
SUFFIX: If this environment variable exists, the SNMP utilities print only the last element of all object IDs with a symbolic name. For more information, see snmpget in the Utilities Reference.
SYSLOG: The node on which syslogd is running.
SYSNAME: The name of the system.

T

TERM: The terminal type.
TERMINFO: The name of the directory for terminfo files; see tic in the Utilities Reference.
TMPDIR: The name of a directory where utilities can create temporary files.
TZ: The timezone definition; see “Setting the time zone” in the Configuring Your Environment chapter of the Neutrino User's Guide.

U

USER: The userid you used to login; the same as LOGNAME.
USER_NAME: Internal use only.