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 <stdio.h> #incl

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 <stdio.h> #include <string.h> 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/$BASHPID/comm' bash Furthermore, https://github.com/torvalds/linux/blob/master/Documentation/filesystems/proc.txt#L1749 https://github.com/torvalds/linux/blob/master/Documentation/... says: > 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm > -------------------------------------------------------- > These files provide a method to access a tasks comm value. It also allows for > a task to set its own or one of its thread siblings comm value. The comm value > is limited in size compared to the cmdline value, so writing anything longer > then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated > comm value. Which works as advertised: dualbus@system76-pc:~$ ~/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 Can you show me an example, in any language, where updating argv[0] causes ps (or /proc/self/comm) to show the updated value? EDIT: formatting. EDIT2: I stand corrected, see willglynn's comment.