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name: FEATURE_ALIASES
de: Command aliases
see: ALIAS
DESCRIPTION:
If defined on compilation of FreeCOM, command aliases are supported.
<P>New aliases are <U>defined</U> using the command:<BR>
EBNF: ALIAS name '=' <<string>>
<P>Aliases are <U>removed</U> using the command:<BR>
EBNF: ALIAS name '='
<P>When FreeCOM is interpreting a command line, the command -- the very
first word -- is matched against all defined aliases. This word is
separated from its arguments by whitespaces and cannot contain any
path delimiters, such as backslashes or colons.
<BR>If the command matches an alias, the name is <U>substituted</U> by the
EBNF!: <<string>>
associated to the aliases, e.g. by defining the alias <CMD>ls</CMD> by:<BR>
CMD: ALIAS ls=dir /w/o
<BR>let FreeCOM interprete the command line:<BR>
CMD: C> ls /a
<BR>exactly as if one had typed in:<BR>
CMD: C> dir /w/o /a
<P>To <U>prevent</U> the alias expansion an asterisk is prefixed before the
command, e.g.:<BR>
CMD: C> *ls /a
<BR>really tries to execute the command:<BR>
CMD: ls /a
<BR>which usually is an external command.
<P>Aliases may be used to <U>hide or re-place internal commands</U>, e.g.:<BR>
CMD: ALIAS dir=xdir
<BR>effectively hides the internal command <CMD>DIR</CMD> and will always
execute the -- usually -- external command <CMD>XDIR</CMD>.
<P>Aliases <U>may be nested</U>, so if both alias definitions mentioned
above are in place, the command:<BR>
CMD: C> ls /a
<BR>is really executed as:<BR>
CMD: xdir /w/o /a
<BR>where the <CMD>ls</CMD> command is substituted by the command
<CMD>dir /w/o</CMD>, then <CMD>dir</CMD> is detected as alias, too, and
hence replaced by <CMD>xdir</CMD>.
<BR>The same alias is <U>never substituted twice</U>, neither directly nor
transitively, so:<BR>
CMD: ALIAS dir=dir /w
<BR>is allowed as well as:<BR>
CMD: ALIAS ls=dir /w/o
CMD: ALIAS dir=ls -l
<BR><TABLE BORDER=1>
<TR>
<TH>command</TH>
<TH>results in</TH>
</TR>
<TR>
<TD><CMD>ls</CMD></TD>
<TD><CMD>ls -l /w/o</CMD></TD>
</TR>
<TR>
<TD><CMD>dir</CMD></TD>
<TD><CMD>dir /w/o -l</CMD></TD>
</TR>
</TABLE>
<P>As implied above, aliases are expanded when needed and <EM>not</EM>
when they are defined.
<P>Aliases are storred <U>for each instance of FreeCOM individually</U>
and are inherited by secondary instances from the parent.
OPTIONS:
Compile-time options:
<UL>
<LI><TT>ALIAS_DEFAULT_SIZE</TT>: The size reserved for all aliases
per FreeCOM instance. Default: 1024
</UL>
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