As glibc, at least, treats it this way.
* linux/aarch64/syscallent.h (getpgrp): Add NF flag.
* linux/alpha/syscallent.h: Likewise.
* linux/arm/syscallent.h: Likewise.
* linux/avr32/syscallent.h: Likewise.
* linux/bfin/syscallent.h: Likewise.
* linux/hppa/syscallent.h: Likewise.
* linux/i386/syscallent.h: Likewise.
* linux/m68k/syscallent.h: Likewise.
* linux/microblaze/syscallent.h: Likewise.
* linux/powerpc/syscallent.h: Likewise.
* linux/powerpc64/syscallent.h: Likewise.
* linux/s390/syscallent.h: Likewise.
* linux/s390x/syscallent.h: Likewise.
* linux/sh/syscallent.h: Likewise.
* linux/sh64/syscallent.h: Likewise.
* linux/sparc/syscallent.h: Likewise.
* linux/sparc64/syscallent.h: Likewise.
* linux/x32/syscallent.h: Likewise.
* linux/x86_64/syscallent.h: Likewise.
* linux/xtensa/syscallent.h: Likewise.
[1057] = { 3, TD, SEN(lseek), "lseek" },
[1058] = { 6, TD|TM|SI, SEN(mmap), "mmap" },
[1059] = { 1, 0, SEN(alarm), "alarm" },
-[1060] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[1060] = { 0, NF, SEN(getpgrp), "getpgrp" },
[1061] = { 0, TS, SEN(pause), "pause" },
[1062] = { 1, 0, SEN(time), "time" },
[1063] = { 2, TF, SEN(utime), "utime" },
[ 60] = { 1, NF, SEN(umask), "umask" },
[ 61] = { 1, TF, SEN(chroot), "chroot" },
[ 62] = { 5, TD|TFST|TSTA, SEN(printargs), "osf_old_fstat" }, /* not implemented */
-[ 63] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 63] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 64] = { 0, 0, SEN(getpagesize), "getpagesize" },
[ 65] = { 5, TM, SEN(printargs), "osf_mremap" }, /* not implemented */
[ 66] = { 0, TP, SEN(vfork), "vfork" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 4, TS, SEN(rt_sigaction), "rt_sigaction" },
[ 68] = { 0, TS, SEN(rt_sigreturn), "rt_sigreturn" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 2, TF, SEN(pivotroot), "pivot_root" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68 ... 71] = { },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 62] = { 2, TSFA, SEN(ustat), "ustat" },
[ 63] = { 2, TD, SEN(dup2), "dup2" },
[ 64] = { 0, NF, SEN(getppid), "getppid" },
-[ 65] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 65] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 66] = { 0, 0, SEN(setsid), "setsid" },
[ 67] = { 3, TS, SEN(sigaction), "sigaction" },
[ 68] = { 0, TS, SEN(sgetmask), "sgetmask" },
[ 78] = { 3, TM, SEN(mincore), "mincore" },
[ 79] = { 2, 0, SEN(getgroups16), "getgroups" },
[ 80] = { 2, 0, SEN(setgroups16), "setgroups" },
-[ 81] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 81] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 82] = { 2, 0, SEN(setgroups), "setgroups32" },
[ 83] = { 3, 0, SEN(setitimer), "setitimer" },
[ 84] = { 3, TD, SEN(ftruncate64), "ftruncate64" },
[ 78] = { 3, TM, SEN(mincore), "mincore" },
[ 79] = { 2, 0, SEN(getgroups), "getgroups" },
[ 80] = { 2, 0, SEN(setgroups), "setgroups" },
-[ 81] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[ 81] = { 0, NF, SEN(getpgrp), "getpgrp" },
[ 82] = { },
[ 83] = { 3, 0, SEN(setitimer), "setitimer" },
[ 84] = { },
[108] = { 0, NF, SEN(getegid), "getegid" },
[109] = { 2, 0, SEN(setpgid), "setpgid" },
[110] = { 0, NF, SEN(getppid), "getppid" },
-[111] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[111] = { 0, NF, SEN(getpgrp), "getpgrp" },
[112] = { 0, 0, SEN(setsid), "setsid" },
[113] = { 2, 0, SEN(setreuid), "setreuid" },
[114] = { 2, 0, SEN(setregid), "setregid" },
[108] = { 0, NF, SEN(getegid), "getegid" },
[109] = { 2, 0, SEN(setpgid), "setpgid" },
[110] = { 0, NF, SEN(getppid), "getppid" },
-[111] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[111] = { 0, NF, SEN(getpgrp), "getpgrp" },
[112] = { 0, 0, SEN(setsid), "setsid" },
[113] = { 2, 0, SEN(setreuid), "setreuid" },
[114] = { 2, 0, SEN(setregid), "setregid" },
[148] = { 2, 0, SEN(setpgid), "setpgid" },
[149] = { 1, 0, SEN(getpgid), "getpgid" },
[150] = { 0, NF, SEN(getppid), "getppid" },
-[151] = { 0, 0, SEN(getpgrp), "getpgrp" },
+[151] = { 0, NF, SEN(getpgrp), "getpgrp" },
[152 ... 153] = { },
[154] = { 1, 0, SEN(times), "times" },
[155] = { 1, TF, SEN(acct), "acct" },