z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

sh
Note: Shell variables that are exported are called ″Environment Variables″, and are
made available in the environment of all commands run from the shell.
Table 28 contains a list of built-in shell variables and also includes
frequently-used environment variables. For more information on environment
variables used by the C-RTL, see the z/OS XL C/C++ Programming Guide. A
list of other environment variables can be found in z/OS UNIX System
Services Planning.
Table 28 lists frequently-used shell variables and their purposes.
Table 28. Built-in Shell Variables (sh command)
Variable Purpose
_ (Underscore) For every command that is run as a child of the shell,
sh sets this variable to the full pathname of the executable file and
passes this value through the environment to that child process.
When processing the MAILPATH variable, this variable holds the
value of the corresponding mail file.
~ (Tilde) expands to value of the HOME directory.
_UNIX03 When _UNIX03 is set to YES, the utilities that have implemented
support for the UNIX03 specification will conform to the UNIX03
specification. This variable is only needed when the syntax or
behavior of UNIX03 conflicts with the existing implementation.
Rule: The value YES must be specified in uppercase.
CDPATH Contains a list of directories for the cd command to search.
Directory names are separated with colons. CDPATH works like the
PATH variable.
COLUMNS Used by several commands to define the width of the terminal
output device.
EDITOR Enables the corresponding editing mode (see set and shedit) when
using vi, emacs, or gmacs.
ENV Contains the path name of a setup script that contains commands
and aliases.
When you invoke sh as a login shell, the ENV script is run after the
login profiles (/etc/profile, $HOME/.profile), before the shell
accepts commands. For other sh invocations, the ENV script is run
before the shell accepts commands. It is typically used to define
shell options, functions and aliases.
sh performs parameter substitution on this value and uses the
results as the name of a setup script. This script is run in the
current shell environment. The ENV variable is usually set in your
.profile.
ERRNO Contains the system error number of the most recently failed
system call. The shell sets this variable only for errors that occur in
the current environment. Assigning a value of 0 to this variable
clears it.
FCEDIT Contains the name of the default editor for the fc command. If this
variable is not set, the default is the ed command.
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