3 files changed, 9 insertions, 2 deletions
diff --git a/NEWS b/NEWS
index e3e7148..d395bc0 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ procps-ng-NEXT
   * library
     Re-add elogind support                                 merge #151
     Used memory is Total - Available
+  * pidwait: Better warning if pidfd_open not implemented
   * pmap: Dont reuse stdin filehandle                      issue #231
   * ps: threads again display when -L is used with -q      issue #234
   * ps: proper aix format string behavior was restored
diff --git a/pgrep.1 b/pgrep.1
index e29e6e1..5e1db7f 100644
--- a/pgrep.1
+++ b/pgrep.1
@@ -7,7 +7,7 @@
 .\" the Free Software Foundation; either version 2 of the License, or
 .\" (at your option) any later version.
 .\"
-.TH PGREP "1" "2021-12-25" "procps-ng" "User Commands"
+.TH PGREP "1" "2022-07-18" "procps-ng" "User Commands"
 .SH NAME
 pgrep, pkill, pidwait \- look up, signal, or wait for processes based on name and other attributes
 .SH SYNOPSIS
@@ -281,7 +281,11 @@ can not be combined.  Let
 me know if you need to do this.
 .PP
 Defunct processes are reported.
-
+.PP
+.B pidwait
+requires the
+.BR pidfd_open (2)
+system call which first appeared in Linux 5.3.
 .SH "SEE ALSO"
 .BR ps (1),
 .BR regex (7),
diff --git a/pgrep.c b/pgrep.c
index 328873b..3a01c78 100644
--- a/pgrep.c
+++ b/pgrep.c
@@ -1064,6 +1064,8 @@ int main (int argc, char **argv)
                 printf(_("waiting for %s (pid %lu)\n"), procs[i].str, procs[i].num);
             int pidfd = pidfd_open(procs[i].num, 0);
             if (pidfd == -1) {
+		if (errno == ENOSYS)
+		    xerrx(EXIT_FAILURE, _("pidfd_open() not implemented in Linux < 5.3"));
                 /* ignore ESRCH, same as pkill */
                 if (errno != ESRCH)
                     xwarn(_("opening pid %ld failed"), procs[i].num);