/proc/pid/comm - command name

/proc/pid/comm (since Linux 2.6.33)

This file exposes the process's comm value—that is, the command name associated with the process. Different threads in the same process may have different comm values, accessible via /proc/pid/task/tid/comm. A thread may modify its comm value, or that of any of other thread in the same thread group (see the discussion of CLONE_THREAD in clone(2)), by writing to the file /proc/self/task/tid/comm. Strings longer than TASK_COMM_LEN (16) characters (including the terminating null byte) are silently truncated.

This file provides a superset of the prctl(2) PR_SET_NAME and PR_GET_NAME operations, and is employed by pthread_setname_np(3) when used to rename threads other than the caller. The value in this file is used for the %e specifier in /proc/sys/kernel/core_pattern; see core(5).

proc(5)