[Info-vax] Unix and DCL shells

[Arne Vajhøj]

On 1/9/2024 2:32 PM, Simon Clubley wrote:
> On 2024-01-08, Lawrence D'Oliveiro <ldo at nz.invalid> wrote:
>> I don?t feel the need for CTRL/T simply because I have something like a
>> dozen or two dozen terminal sessions open at any one time, and it is easy
>> enough to check up on a hung-looking process from another session. I can
>> even rummage around in procfs to check the status of open files and memory
>> usage in the problem process, which is way more than you can do with CTRL/
>> T anyway.
> 
> Programs can intercept Ctrl-T and output program-specific information.

Yes - it is a choice whether to use DCL default or a program
specific handler.

$ type some1.c
#include <stdio.h>

int main(int argc, char *argv[])
{
    puts("Press enter to exit");
    getchar();
    return 0;
}
$ cc some1
$ link some1
$ r some1
Press enter to exit

ARNE4::ARNE 20:31:33 some1     CPU=00:00:12.63 PF=95154 IO=13861 MEM=330
ARNE4::ARNE 20:31:33 some1     CPU=00:00:12.63 PF=95155 IO=13862 MEM=331
ARNE4::ARNE 20:31:34 some1     CPU=00:00:12.63 PF=95155 IO=13863 MEM=331

$ type some2.c
#include <stdio.h>

#include <descrip.h>
#include <iodef.h>
#include <libclidef.h>
#include <lib$routines.h>
#include <starlet.h>

static int n = 0;

void catcher(int c)
{
    n++;
    printf("You pressed CTRL/T %d times\n", n);
}

int main(int argc, char *argv[])
{
    long newmask, oldmask, oobmask;
    $DESCRIPTOR(ttdesc, "TT:");
    short chan;
    newmask = LIB$M_CLI_CTRLT;
    lib$disable_ctrl(&newmask, &oldmask);
    sys$assign(&ttdesc, &chan, 0, 0);
    oobmask = 1 << ('T' - 'A');
    sys$qiow(0, chan, IO$_SETMODE|IO$M_OUTBAND, 0, 0, 0, catcher, 
&oobmask, 0, 0, 0, 0);
    puts("Press enter to exit");
    getchar();
    lib$enable_ctrl(&oldmask);
    sys$dassgn(chan);
    return 0;
}
$ cc some2
$ link some2
$ r some2
Press enter to exit

You pressed CTRL/T 1 times
You pressed CTRL/T 2 times
You pressed CTRL/T 3 times

Arne

PS: And note that I managed to get something strongly VMS
     related into the post!