🚀 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
>
>
>
>
>
>
>
>
>

In article <3suhtc$bi4@news.duke.edu>, yang@math.duke.edu (Joe Yang) wrote:

> "system" is not a good way (although convinient) to apawn another
> program in a C program anyway, 

how about in a csh script?  good?  bad?

-- 
"Wheeeee, doggies!"

                     - jed clampett

In article <3sprhr$6g6@venera.isi.edu>, gsingh@isi.edu (Gaurav Singh) says:

>
>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
>


looks to me like you're shelling out to a bourne shell, judging
from your err msg, and the alias cmd is in the C shell.

off the top of my head try:

		system("tcsh test");

markjr@shmooze.net (Landslidius MarXaMis) writes:

>In article <3sprhr$6g6@venera.isi.edu>, gsingh@isi.edu (Gaurav Singh) says:

>>
>>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
>>


>looks to me like you're shelling out to a bourne shell, judging
>from your err msg, and the alias cmd is in the C shell.

>off the top of my head try:

>		system("tcsh test");

or specify the full pathname of test.

Thanh Ma
tma@encore.com