More questions about how to issue a C-SHELL command within a C program

[Frank P. Bresz]

In article <1990Aug15.221504.348 at iwarp.intel.com> merlyn at iwarp.intel.com (Randal Schwartz) writes:
>In article <25285.26c9113d at kuhub.cc.ukans.edu>, jian at kuhub writes:

	[ Stuff deleted ]

>|         execlp("/bin/csh", "csh", "-c", "setenv TERM adm3a", (char *) 0);
>| 
>| There was not any runtime errors if I embeded one of above statements into my
>| C program. But none of them can change the terminal type. I don't know why.
>| Would someone point me another way to change terminal type within a C program
>| or give me some hints what I did wrong. I would appreciate any helps.

>The short answer:

>You *cannot* change an environment variable (such as TERM) from a
>child process.  The shell provides a *copy* of its environment to the
>children processes (such as your C program), so changes to that copy
>(or in your case, using a further csh which has its *own* copy), will
>not affect the parent shell.  This is by design, so don't ask "Well,
>are they going to fix this some day?"

	Why not just use the putenv system call with something akin to:

putenv("TERM=adm3a");	/* notify subprocess that it is an adm3a terminal */


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