Earlier quoted context omitted.
Can you show an example of how this would work with BASH_ARGV0?
Sorry I don’t know anything about how Bash is implemented, but when someone assigns to that variable Bash just needs to write that string to argv.
I tried python, bash and even C, none of them update /proc/self/comm when argv[0] is updated:
dualbus@system76-pc:~$ cat argv0.c
#include
#include
int main(int argc, char **argv) {
FILE *fp;
char buf[256]; // XXX :-)
strcpy(argv[0], "XYZ");
//puts(argv[0]);
fp = fopen("/proc/self/comm", "r");
fread(&buf, 1, 256, fp);
buf[255] = '\0';
puts(buf);
}
dualbus@system76-pc:~$ gcc -o argv0 argv0.c -Wall
dualbus@system76-pc:~$ ./argv0
argv0
dualbus@system76-pc:~$ python -c 'import sys; sys.argv[0] = "XYZ"; print(open("/proc/self/comm").read())'
python
dualbus@system76-pc:~$ ~/src/gnu/bash/bash -c 'BASH_ARGV0="XYZ"; cat /proc/$BASHPID/comm'
bash
> 3.6 /proc//comm & /proc//task//comm
> --------------------------------------------------------
> These files provide a method to access a tasks comm value. It also allows for
> a task to set its own or one of its thread siblings comm value. The comm value
> is limited in size compared to the cmdline value, so writing anything longer
> then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
> comm value.
dualbus@system76-pc:~$ ~/src/gnu/bash/bash -c 'echo -n XYZ > /proc/$BASHPID/comm; ps -p $BASHPID'
PID TTY TIME CMD
28797 pts/6 00:00:00 XYZ
EDIT: formatting.
EDIT2: I stand corrected, see willglynn's comment.