.\" Copyright (C) 2012 Chandan Apsangi .\" and Copyright (C) 2013 Michael Kerrisk .\" .\" %%%LICENSE_START(VERBATIM) .\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are .\" preserved on all copies. .\" .\" Permission is granted to copy and distribute modified versions of this .\" manual under the conditions for verbatim copying, provided that the .\" entire resulting derived work is distributed under the terms of a .\" permission notice identical to this one. .\" .\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date. The author(s) assume no .\" responsibility for errors or omissions, or for damages resulting from .\" the use of the information contained herein. The author(s) may not .\" have taken the same level of care in the production of this manual, .\" which is licensed free of charge, as they might when working .\" professionally. .\" .\" Formatted or processed versions of this manual, if unaccompanied by .\" the source, must acknowledge the copyright and authors of this work. .\" %%%LICENSE_END .\" .TH PTHREAD_SETNAME_NP 3 2020-11-01 "Linux" "Linux Programmer's Manual" .SH NAME pthread_setname_np, pthread_getname_np \- set/get the name of a thread .SH SYNOPSIS .nf .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" .B #include .BI "int pthread_setname_np(pthread_t " thread ", const char *" name ); .BI "int pthread_getname_np(pthread_t " thread , .BI " char *" name ", size_t " len ); .fi .PP Compile and link with \fI\-pthread\fP. .SH DESCRIPTION By default, all the threads created using .BR pthread_create () inherit the program name. The .BR pthread_setname_np () function can be used to set a unique name for a thread, which can be useful for debugging multithreaded applications. The thread name is a meaningful C language string, whose length is restricted to 16 characters, including the terminating null byte (\(aq\e0\(aq). The .I thread argument specifies the thread whose name is to be changed; .I name specifies the new name. .PP The .BR pthread_getname_np () function can be used to retrieve the name of the thread. The .I thread argument specifies the thread whose name is to be retrieved. The buffer .I name is used to return the thread name; .I len specifies the number of bytes available in .IR name . The buffer specified by .I name should be at least 16 characters in length. The returned thread name in the output buffer will be null terminated. .SH RETURN VALUE On success, these functions return 0; on error, they return a nonzero error number. .SH ERRORS The .BR pthread_setname_np () function can fail with the following error: .TP .B ERANGE The length of the string specified pointed to by .I name exceeds the allowed limit. .PP The .BR pthread_getname_np () function can fail with the following error: .TP .B ERANGE The buffer specified by .I name and .I len is too small to hold the thread name. .PP If either of these functions fails to open .IR /proc/self/task/[tid]/comm , then the call may fail with one of the errors described in .BR open (2). .SH VERSIONS These functions first appeared in glibc in version 2.12. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbw21 lb lb l l l. Interface Attribute Value T{ .BR pthread_setname_np (), .BR pthread_getname_np () T} Thread safety MT-Safe .TE .sp 1 .SH CONFORMING TO These functions are nonstandard GNU extensions; hence the suffix "_np" (nonportable) in the names. .SH NOTES .BR pthread_setname_np () internally writes to the thread-specific .I comm file under the .IR /proc filesystem: .IR /proc/self/task/[tid]/comm . .BR pthread_getname_np () retrieves it from the same location. .SH EXAMPLES The program below demonstrates the use of .BR pthread_setname_np () and .BR pthread_getname_np (). .PP The following shell session shows a sample run of the program: .PP .in +4n .EX .RB "$" " ./a.out" Created a thread. Default name is: a.out The thread name after setting it is THREADFOO. \fB\(haZ\fP # Suspend the program [1]+ Stopped ./a.out .RB "$ " "ps H \-C a.out \-o \(aqpid tid cmd comm\(aq" PID TID CMD COMMAND 5990 5990 ./a.out a.out 5990 5991 ./a.out THREADFOO .RB "$ " "cat /proc/5990/task/5990/comm" a.out .RB "$ " "cat /proc/5990/task/5991/comm" THREADFOO .EE .in .SS Program source \& .EX #define _GNU_SOURCE #include #include #include #include #include #include #define NAMELEN 16 #define errExitEN(en, msg) \e do { errno = en; perror(msg); \e exit(EXIT_FAILURE); } while (0) static void * threadfunc(void *parm) { sleep(5); // allow main program to set the thread name return NULL; } int main(int argc, char **argv) { pthread_t thread; int rc; char thread_name[NAMELEN]; rc = pthread_create(&thread, NULL, threadfunc, NULL); if (rc != 0) errExitEN(rc, "pthread_create"); rc = pthread_getname_np(thread, thread_name, NAMELEN); if (rc != 0) errExitEN(rc, "pthread_getname_np"); printf("Created a thread. Default name is: %s\en", thread_name); rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO"); if (rc != 0) errExitEN(rc, "pthread_setname_np"); sleep(2); rc = pthread_getname_np(thread, thread_name, (argc > 2) ? atoi(argv[1]) : NAMELEN); if (rc != 0) errExitEN(rc, "pthread_getname_np"); printf("The thread name after setting it is %s.\en", thread_name); rc = pthread_join(thread, NULL); if (rc != 0) errExitEN(rc, "pthread_join"); printf("Done\en"); exit(EXIT_SUCCESS); } .EE .SH SEE ALSO .ad l .nh .BR prctl (2), .BR pthread_create (3), .BR pthreads (7) .SH COLOPHON This page is part of release 5.10 of the Linux .I man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at \%https://www.kernel.org/doc/man\-pages/.