🚀 go-pugleaf

In article <3sprhr$6g6@venera.isi.edu>, Gaurav Singh <gsingh@isi.edu> wrote:
>
>Hi,
>
>	I am trying to execute the "system" command to execute an application
>(executable program).
>However the system command does not work if the name of the application has been
>aliased.
>
>	e.g: $ alias test ps
>	     $ test
>		(this works)
>	
>	however system("test"); in a c-program does not work.
>
>	sh: test: not found
>
>	
>	I wonder if there is a way to force the system command to take into
>account the aliases, or is there a more efficient way to invoke an application
>from a c-program.
>

The reason this doesn't work is because the "system" library routine
spawns a Bourne shell process first, then execute the command in the
new shell.  First of all, aliases are not part of the environment
inherited by a child process ("sh" in this case), secondly, alias is
a C shell command and Boune shell doesn't even understand it.

"system" is not a good way (although convinient) to apawn another
program in a C program anyway, one of the disadventage is the overhead
because another shell process is spawned unnecessarily.  Try using
system call "fork" to create a new process directly and then using 
exec (or one of its variations) to execute the new program.  Now this
will not solve your alias program, because an alias is not a physical
program.  Is there any particular reason you have to use an alias?
this will make your grogram very "unportable" even from shell to
shell.


Rose Sun
rose@ais.com

 


>	pl reply to this news group or to gsingh@isi.edu
>
>
>	thanks a ton
>
>	Gaurav
>
>
>
>
>
>
>
>
>