diff -up ./lsof.8.ori ./lsof.8

--- ./lsof.8.ori	2018-02-20 16:45:18.347856323 +0100

+++ ./lsof.8	2018-02-20 16:45:26.204823914 +0100

@@ -6,7 +6,7 @@ lsof \- list open files

 .SH SYNOPSIS

 .B lsof

 [

-.B \-?abChKlnNOPRtUvVX

+.B \-?abChlnNOPRtUvVX

 ] [

 .BI -A " A"

 ] [

@@ -30,6 +30,8 @@ lsof \- list open files

 ] [

 .BI \-k " k"

 ] [

+.BI \-K " k"

+] [

 .BI +|\-L " [l]"

 ] [

 .BI +|\-m " m"

@@ -963,7 +965,7 @@ Here are some sample addresses:

 	:time \- either TCP, UDP or UDPLITE time service port

 .fi

 .TP \w'names'u+4

-.B \-K

+.BI \-K " k"

 selects the listing of tasks (threads) of processes, on dialects

 where task (thread) reporting is supported.

 (If help output \- i.e., the output of the

@@ -973,6 +975,15 @@ or

 options \- shows this option, then task (thread) reporting is

 supported by the dialect.)

 .IP

+If

+.B \-K

+is followed by a value,

+.IR k ,

+it must be ``i''.  That causes

+.I lsof

+to ignore tasks, particularly in the default, list\-everything case

+when no other options are specified.

+.IP

 When

 .B \-K

 and

diff -up ./lsof.h.ori ./lsof.h

--- ./lsof.h.ori	2018-02-19 17:41:00.082833606 +0100

+++ ./lsof.h	2018-02-19 18:39:40.336086710 +0100

@@ -491,6 +491,8 @@ struct afsnode {			/* AFS pseudo-node st

 };

 # endif	/* defined(HAS_AFS) */

+extern int AllProc;

+

 # if	defined(HAS_STD_CLONE)

 struct clone {

 	int dx;			/* index of device entry in Devtp[] */

@@ -672,6 +674,7 @@ extern struct fieldsel FieldSel[];

 extern int Hdr;

 enum IDType {PGID, PID};

+extern int  IgnTasks;

 extern char *InodeFmt_d;

 extern char *InodeFmt_x;

 extern int LastPid;

@@ -938,8 +941,9 @@ extern int Procsrch;

 extern int PrPass;

 extern int RptTm;

 extern struct l_dev **Sdev;

-extern int Selall;

+extern int SelAll;

 extern int Selflags;

+extern int SelProc;

 extern int Setgid;

 extern int Selinet;

 extern int Setuidroot;

diff -up ./main.c.ori ./main.c

--- ./main.c.ori	2018-02-19 17:20:33.058670928 +0100

+++ ./main.c	2018-02-19 18:26:41.245793075 +0100

@@ -181,7 +181,7 @@ main(argc, argv)

 #endif	/* defined(HASKOPT) */

 #if	defined(HASTASKS)

-	    "K",

+	    "K:",

 #else	/* !defined(HASTASKS) */

 	    "",

 #endif	/* defined(HASTASKS) */

@@ -575,10 +575,27 @@ main(argc, argv)

 #endif	/* defined(HASKOPT) */

 #if	defined(HASTASKS)

-		case 'K':

+	    case 'K':

+		if (!GOv || *GOv == '-' || *GOv == '+') {

 		    Ftask = 1;

+		    IgnTasks = 0;

 		    Selflags |= SELTASK;

-		    break;

+		    if (GOv) {

+			GOx1 = GObk[0];

+			GOx2 = GObk[1];

+		    }

+		} else {

+		    if (!strcasecmp(GOv, "i")) {

+			Ftask = 0;

+			IgnTasks = 1;

+			Selflags &= ~SELTASK;

+		   } else {

+			(void) fprintf(stderr,

+			    "%s: -K not followed by i (but by %s)\n", Pn, GOv);

+			err = 1;

+		   }

+		}

+		break;

 #endif	/* defined(HASTASKS) */

 	    case 'l':

@@ -966,6 +983,11 @@ main(argc, argv)

 	    }

 	}

 /*

+ * If IgnTasks is set, remove SELTASK from SelAll and SelProc.

+ */

+	SelAll = IgnTasks ? (SELALL & ~SELTASK) : SELALL;

+	SelProc = IgnTasks ? (SELPROC & ~SELTASK) : SELPROC;

+/*

  * Check for argument consistency.

  */

 	if (Cmdnx && Cmdni) {

@@ -1143,12 +1165,12 @@ main(argc, argv)

 		    "%s: no select options to AND via -a\n", Pn);

 		usage(1, 0, 0);

 	    }

-	    Selflags = SELALL;

+	    Selflags = SelAll;

 	} else {

 	    if (GOx1 >= argc && (Selflags & (SELNA|SELNET)) != 0

 	    &&  (Selflags & ~(SELNA|SELNET)) == 0)

 		Selinet = 1;

-	    Selall = 0;

+	    AllProc = 0;

 	}

 /*

  * Get the device for DEVDEV_PATH.

diff -up ./proc.c.ori ./proc.c

--- ./proc.c.ori	2018-02-19 18:39:57.188006540 +0100

+++ ./proc.c	2018-02-19 18:44:33.993689693 +0100

@@ -498,7 +498,7 @@ examine_lproc()

  *	o  listing is selected by an ANDed option set (not all options)

  *	   that includes a single PID selection -- this one.

  */

-	if ((Lp->sf & SELPID) && !Selall) {

+	if ((Lp->sf & SELPID) && !AllProc) {

 	    if ((Selflags == SELPID)

 	    ||  (Fand && (Selflags & SELPID))) {

 		sbp = 1;

@@ -648,7 +648,7 @@ is_file_sel(lp, lf)

 	}

 #endif	/* defined(HASSECURITY) && defined(HASNOSOCKSECURITY) */

-	if (Selall)

+	if (AllProc)

 	    return(1);

 	if (Fand && ((lf->sf & Selflags) != Selflags))

 	    return(0);

@@ -742,13 +742,13 @@ is_proc_excl(pid, pgid, uid, pss, sf)

  * network selections from the file flags, so that the tests in is_file_sel()

  * work as expected.

  */

-	if (Selall) {

+	if (AllProc) {

 	    *pss = PS_PRI;

 #if	defined(HASSECURITY) && defined(HASNOSOCKSECURITY)

-	    *sf = SELALL & ~(SELNA | SELNET);

+	    *sf = SelAll & ~(SELNA | SELNET);

 #else	/* !defined(HASSECURITY) || !defined(HASNOSOCKSECURITY) */

-	    *sf = SELALL;

+	    *sf = SelAll;

 #endif	/* defined(HASSECURITY) && defined(HASNOSOCKSECURITY) */

 	    return(0);

diff -up ./store.c.ori ./store.c

--- ./store.c.ori	2018-02-19 18:39:50.532038205 +0100

+++ ./store.c	2018-02-19 18:42:57.828147181 +0100

@@ -43,6 +43,8 @@ static char *rcsid = "$Id: store.c,v 1.4

  * Global storage definitions

  */

+int AllProc = 1;		/* all processes are selected (default) */

+

 #if	defined(HASBLKDEV)

 struct l_dev *BDevtp = (struct l_dev *)NULL;

 				/* block device table pointer */

@@ -236,6 +238,7 @@ struct fieldsel FieldSel[] = {

 };

 int Hdr = 0;			/* header print status */

+int IgnTasks = 0;		/* ignore tasks when non-zero */

 char *InodeFmt_d = (char *) NULL;

 				/* INODETYPE decimal printf specification */

 char *InodeFmt_x = (char *) NULL;

@@ -320,8 +323,9 @@ int RptTm = 0;			/* repeat time -- set b

 struct l_dev **Sdev = (struct l_dev **)NULL;

 				/* pointer to Devtp[] pointers, sorted

 				 * by device */

-int Selall = 1;			/* all processes are selected (default) */

+int SelAll = 0;			/* SELALL flags, modified by IgnTasks */

 int Selflags = 0;		/* selection flags -- see SEL* in lsof.h */

+int SelProc = 0;		/* SELPROC flags, modified by IgnTasks */

 int Setgid = 0;			/* setgid state */

 int Selinet = 0;		/* select only Internet socket files */

 int Setuidroot = 0;		/* setuid-root state */

diff -up ./dialects/linux/dproc.c.ori ./dialects/linux/dproc.c

--- ./dialects/linux/dproc.c.ori	2018-02-21 14:32:56.779061847 +0100

+++ ./dialects/linux/dproc.c	2018-02-21 16:10:53.896590180 +0100

@@ -228,7 +228,7 @@ gather_proc_info()

 	     * If only ORed process selection options have been specified,

 	     * enable conditional file skipping and socket file only checking.

 	     */

-		if ((Selflags & SELFILE) || !(Selflags & SELPROC))

+		if ((Selflags & SELFILE) || !(Selflags & SelProc))

 		    Cckreg = Ckscko = 0;

 		else

 		    Cckreg = Ckscko = 1;