From 33284944c618a04eccfb9645123bb2dd7eaa64b5 Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:10:50 +0000
Subject: [PATCH 1/8] feat: add -J/-j option parsing for JSON output

Add Fjson/Fjsonl global flags, option parsing for -J (nested JSON)
and -j (JSON Lines), mutual exclusivity validation, and default
field selection when -F is not explicitly given.
---
 lib/common.h |  3 ++
 src/main.c   | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/store.c  |  3 ++
 3 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/lib/common.h b/lib/common.h
index 1e6c67ee..d5beb43e 100644
--- a/lib/common.h
+++ b/lib/common.h
@@ -684,6 +684,9 @@ extern int ErrStat;
 extern uid_t Euid;
 extern int Fcntx;
 extern int Ffield;
+extern int Fjson;
+extern int Fjsonl;
+extern int Fjson_first_proc;
 extern int Ffilesys;
 extern int Fhelp;
 extern int Fhost;
diff --git a/src/main.c b/src/main.c
index 0c2e98a0..199ffe1d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -151,7 +151,7 @@ int main(int argc, char *argv[]) {
      * Create option mask.
      */
     (void)snpf(options, sizeof(options),
-               "?a%sbc:%sD:d:%s%sf:F:g:hHi:%s%slL:%s%snNo:Op:QPr:%ss:S:tT:u:"
+               "?a%sbc:%sD:d:%s%sf:F:g:hHi:%s%sJjlL:%s%snNo:Op:QPr:%ss:S:tT:u:"
                "UvVwx:%s%s%s",
 
 #if defined(HAS_AFS) && defined(HASAOPT)
@@ -556,6 +556,24 @@ int main(int argc, char *argv[]) {
         case '?':
             Fhelp = 1;
             break;
+        case 'J':
+            if (GOp == '+') {
+                (void)fprintf(stderr, "%s: +J is not supported\n", Pn);
+                err = 1;
+                break;
+            }
+            Fjson = 1;
+            Ffield = 1;
+            break;
+        case 'j':
+            if (GOp == '+') {
+                (void)fprintf(stderr, "%s: +j is not supported\n", Pn);
+                err = 1;
+                break;
+            }
+            Fjsonl = 1;
+            Ffield = 1;
+            break;
         case 'i':
             if (!GOv || *GOv == '-' || *GOv == '+') {
                 Fnet = 1;
@@ -1097,6 +1115,14 @@ int main(int argc, char *argv[]) {
         (void)fprintf(stderr, "%s: -x must accompany +d or +D\n", Pn);
         err++;
     }
+    if (Fjson && Fjsonl) {
+        (void)fprintf(stderr, "%s: -J and -j are mutually exclusive\n", Pn);
+        err++;
+    }
+    if ((Fjson || Fjsonl) && Fterse) {
+        (void)fprintf(stderr, "%s: -J/-j and -t are mutually exclusive\n", Pn);
+        err++;
+    }
 
 #if defined(HASEOPT)
     if (Efsysl) {
@@ -1126,6 +1152,58 @@ int main(int argc, char *argv[]) {
     }
 #endif /* defined(HASEOPT) */
 
+    /*
+     * If -J/-j was given, ensure field selections are set.
+     * If -F was also given with field chars, those selections are already
+     * in FieldSel[]. Otherwise, enable the default field set.
+     */
+    if (Fjson || Fjsonl) {
+        int has_fields = 0;
+        for (i = 0; FieldSel[i].nm; i++) {
+            if (FieldSel[i].st && FieldSel[i].id != LSOF_FID_PID &&
+                FieldSel[i].id != LSOF_FID_MARK) {
+                has_fields = 1;
+                break;
+            }
+        }
+        if (!has_fields) {
+            for (i = 0; FieldSel[i].nm; i++) {
+#if !defined(HASPPID)
+                if (FieldSel[i].id == LSOF_FID_PPID)
+                    continue;
+#endif
+#if !defined(HASTASKS)
+                if (FieldSel[i].id == LSOF_FID_TCMD ||
+                    FieldSel[i].id == LSOF_FID_TID)
+                    continue;
+#endif
+#if !defined(HASFSTRUCT)
+                if (FieldSel[i].id == LSOF_FID_CT ||
+                    FieldSel[i].id == LSOF_FID_FA ||
+                    FieldSel[i].id == LSOF_FID_FG ||
+                    FieldSel[i].id == LSOF_FID_NI)
+                    continue;
+#endif
+#if defined(HASSELINUX)
+                if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
+                    continue;
+#else
+                if (FieldSel[i].id == LSOF_FID_CNTX)
+                    continue;
+#endif
+                if (FieldSel[i].id == LSOF_FID_RDEV)
+                    continue;
+#if !defined(HASZONES)
+                if (FieldSel[i].id == LSOF_FID_ZONE)
+                    continue;
+#endif
+                FieldSel[i].st = 1;
+                if (FieldSel[i].opt && FieldSel[i].ov)
+                    *(FieldSel[i].opt) |= FieldSel[i].ov;
+            }
+        }
+    }
+
     if (DChelp || err || Fhelp || fh || version)
         usage(ctx, err ? 1 : 0, fh, version);
     /*
diff --git a/src/store.c b/src/store.c
index 8e7dfd25..a51c49cf 100644
--- a/src/store.c
+++ b/src/store.c
@@ -72,6 +72,9 @@ int NcacheReload = 1; /* 1 == call ncache_load() */
 #endif                /* defined(HASNCACHE) */
 
 int Ffield = 0;  /* -f and -F status */
+int Fjson = 0;   /* -J JSON output status */
+int Fjsonl = 0;  /* -j JSON Lines output status */
+int Fjson_first_proc = 1; /* first process flag for JSON comma handling */
 int FgColW;      /* FILE-FLAG column width */
 int Fhelp = 0;   /* -h option status */
 int Fhost = 1;   /* -H option status */

From f221123f9228c2128a2860d2834a340f634ba7be Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:13:54 +0000
Subject: [PATCH 2/8] feat: add JSON string escaping and output helpers

---
 src/print.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/src/print.c b/src/print.c
index 494f9eb3..ed8e0b56 100644
--- a/src/print.c
+++ b/src/print.c
@@ -31,6 +31,7 @@
 #include "common.h"
 #include "cli.h"
 #include "proto.h"
+#include <inttypes.h>
 
 /*
  * Local definitions, structures and function prototypes
@@ -93,6 +94,83 @@ static char *lkup_svcnam(struct lsof_context *ctx, int h, int p, int pr,
 static int printinaddr(struct lsof_context *ctx);
 static int human_readable_size(SZOFFTYPE sz, int print, int col);
 
+/*
+ * JSON output helpers
+ */
+
+static void json_puts_escaped(const char *s) {
+    const unsigned char *p = (const unsigned char *)s;
+    while (*p) {
+        switch (*p) {
+        case '"':
+            fputs("\\\"", stdout);
+            break;
+        case '\\':
+            fputs("\\\\", stdout);
+            break;
+        case '\b':
+            fputs("\\b", stdout);
+            break;
+        case '\f':
+            fputs("\\f", stdout);
+            break;
+        case '\n':
+            fputs("\\n", stdout);
+            break;
+        case '\r':
+            fputs("\\r", stdout);
+            break;
+        case '\t':
+            fputs("\\t", stdout);
+            break;
+        default:
+            if (*p < 0x20)
+                printf("\\u%04x", (unsigned int)*p);
+            else
+                putchar(*p);
+            break;
+        }
+        p++;
+    }
+}
+
+static void json_print_str(int *sep, const char *key, const char *val) {
+    if (*sep)
+        putchar(',');
+    printf("\"%s\":\"", key);
+    json_puts_escaped(val);
+    putchar('"');
+    *sep = 1;
+}
+
+static void json_print_int(int *sep, const char *key, int val) {
+    if (*sep)
+        putchar(',');
+    printf("\"%s\":%d", key, val);
+    *sep = 1;
+}
+
+static void json_print_uint64_str(int *sep, const char *key, uint64_t val) {
+    if (*sep)
+        putchar(',');
+    printf("\"%s\":\"%" PRIu64 "\"", key, val);
+    *sep = 1;
+}
+
+static void json_print_long(int *sep, const char *key, long val) {
+    if (*sep)
+        putchar(',');
+    printf("\"%s\":%ld", key, val);
+    *sep = 1;
+}
+
+static void json_print_ulong(int *sep, const char *key, unsigned long val) {
+    if (*sep)
+        putchar(',');
+    printf("\"%s\":%lu", key, val);
+    *sep = 1;
+}
+
 #if !defined(HASNORPC_H)
 /*
  * fill_portmap() -- fill the RPC portmap program name table via a conversation

From cf0b102b50914214e5af562751fa6c25b609c01b Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:21:29 +0000
Subject: [PATCH 3/8] feat: implement JSON process/file printing for -J/-j

---
 src/print.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 224 insertions(+)

diff --git a/src/print.c b/src/print.c
index ed8e0b56..29ca3ad5 100644
--- a/src/print.c
+++ b/src/print.c
@@ -1865,6 +1865,180 @@ int human_readable_size(SZOFFTYPE sz, int print, int col) {
     return strlen(buf);
 }
 
+/*
+ * json_print_file() - print a single file entry as JSON fields
+ */
+static void json_print_file(struct lsof_context *ctx, int *sep) {
+    char buf[128];
+    char fd_str[FDLEN];
+    char type[TYPEL];
+    char *cp;
+    unsigned long ul;
+
+    if (FieldSel[LSOF_FIX_FD].st) {
+        if (Lf->fd_type == LSOF_FD_NUMERIC) {
+            char num_buf[32];
+            snprintf(num_buf, sizeof(num_buf), "%d", Lf->fd_num);
+            json_print_str(sep, "fd", num_buf);
+        } else {
+            fd_to_string(Lf->fd_type, Lf->fd_num, fd_str);
+            json_print_str(sep, "fd", fd_str);
+        }
+    }
+    if (FieldSel[LSOF_FIX_ACCESS].st) {
+        char a[2] = {access_to_char(Lf->access), '\0'};
+        if (a[0] != ' ')
+            json_print_str(sep, "access", a);
+    }
+    if (FieldSel[LSOF_FIX_LOCK].st) {
+        char l[2] = {lock_to_char(Lf->lock), '\0'};
+        if (l[0] != ' ')
+            json_print_str(sep, "lock", l);
+    }
+    if (FieldSel[LSOF_FIX_TYPE].st && Lf->type != LSOF_FILE_NONE) {
+        file_type_to_string(Lf->type, Lf->unknown_file_type_number, type,
+                            TYPEL);
+        json_print_str(sep, "type", type);
+    }
+    if (FieldSel[LSOF_FIX_DEVCH].st && Lf->dev_ch && Lf->dev_ch[0]) {
+        for (cp = Lf->dev_ch; *cp == ' '; cp++)
+            ;
+        if (*cp)
+            json_print_str(sep, "device", cp);
+    }
+    if (FieldSel[LSOF_FIX_DEVN].st && Lf->dev_def) {
+        if (sizeof(unsigned long) > sizeof(dev_t))
+            ul = (unsigned long)((unsigned int)Lf->dev);
+        else
+            ul = (unsigned long)Lf->dev;
+        snprintf(buf, sizeof(buf), "0x%lx", ul);
+        json_print_str(sep, "device_number", buf);
+    }
+    if (FieldSel[LSOF_FIX_RDEV].st && Lf->rdev_def) {
+        if (sizeof(unsigned long) > sizeof(dev_t))
+            ul = (unsigned long)((unsigned int)Lf->rdev);
+        else
+            ul = (unsigned long)Lf->rdev;
+        snprintf(buf, sizeof(buf), "0x%lx", ul);
+        json_print_str(sep, "raw_device", buf);
+    }
+    if (FieldSel[LSOF_FIX_SIZE].st && Lf->sz_def) {
+        json_print_uint64_str(sep, "size", (uint64_t)Lf->sz);
+    }
+    if (FieldSel[LSOF_FIX_OFFSET].st && Lf->off_def) {
+        json_print_uint64_str(sep, "offset", (uint64_t)Lf->off);
+    }
+    if (FieldSel[LSOF_FIX_INODE].st && Lf->inp_ty == 1) {
+        json_print_uint64_str(sep, "inode", (uint64_t)Lf->inode);
+    }
+    if (FieldSel[LSOF_FIX_NLINK].st && Lf->nlink_def) {
+        json_print_long(sep, "nlink", Lf->nlink);
+    }
+    if (FieldSel[LSOF_FIX_PROTO].st && Lf->inp_ty == 2) {
+        for (cp = Lf->iproto; *cp == ' '; cp++)
+            ;
+        if (*cp)
+            json_print_str(sep, "protocol", cp);
+    }
+
+#if defined(HASFSTRUCT)
+    if (FieldSel[LSOF_FIX_FG].st && (Fsv & FSV_FG) && (Lf->fsv & FSV_FG) &&
+        (FsvFlagX || Lf->ffg || Lf->pof)) {
+        json_print_str(sep, "flags", print_fflags(ctx, Lf->ffg, Lf->pof));
+    }
+#endif /* defined(HASFSTRUCT) */
+
+    if (FieldSel[LSOF_FIX_NAME].st && Lf->nm) {
+        json_print_str(sep, "name", Lf->nm);
+    }
+
+    /* TCP/TPI info as nested object */
+    if (Lf->lts.type >= 0 && FieldSel[LSOF_FIX_TCPTPI].st) {
+        if (*sep)
+            putchar(',');
+        printf("\"tcp_info\":{");
+        int tsep = 0;
+
+        if ((Ftcptpi & TCPTPI_STATE) && Lf->lts.type == 0) {
+            if (!TcpNstates)
+                (void)build_IPstates(ctx);
+            int s = Lf->lts.state.i;
+            if (s >= 0 && s < TcpNstates && TcpSt[s])
+                json_print_str(&tsep, "state", TcpSt[s]);
+            else {
+                snprintf(buf, sizeof(buf), "UNKNOWN_%d", s);
+                json_print_str(&tsep, "state", buf);
+            }
+        }
+#if defined(HASTCPTPIQ)
+        if (Ftcptpi & TCPTPI_QUEUES) {
+            if (Lf->lts.rqs)
+                json_print_ulong(&tsep, "recv_queue", Lf->lts.rq);
+            if (Lf->lts.sqs)
+                json_print_ulong(&tsep, "send_queue", Lf->lts.sq);
+        }
+#endif /* defined(HASTCPTPIQ) */
+#if defined(HASTCPTPIW)
+        if (Ftcptpi & TCPTPI_WINDOWS) {
+            if (Lf->lts.rws)
+                json_print_ulong(&tsep, "read_window", Lf->lts.rw);
+            if (Lf->lts.wws)
+                json_print_ulong(&tsep, "write_window", Lf->lts.ww);
+        }
+#endif /* defined(HASTCPTPIW) */
+        putchar('}');
+        *sep = 1;
+    }
+}
+
+/*
+ * json_print_proc_fields() - print process-level JSON fields
+ */
+static void json_print_proc_fields(struct lsof_context *ctx, int *sep) {
+    int ty;
+    char *cp;
+
+    if (FieldSel[LSOF_FIX_PID].st)
+        json_print_int(sep, "pid", Lp->pid);
+
+#if defined(HASTASKS)
+    if (FieldSel[LSOF_FIX_TID].st && Lp->tid)
+        json_print_int(sep, "tid", Lp->tid);
+    if (FieldSel[LSOF_FIX_TCMD].st && Lp->tcmd)
+        json_print_str(sep, "task_cmd", Lp->tcmd);
+#endif
+
+#if defined(HASZONES)
+    if (FieldSel[LSOF_FIX_ZONE].st && Fzone && Lp->zn)
+        json_print_str(sep, "zone", Lp->zn);
+#endif
+
+#if defined(HASSELINUX)
+    if (FieldSel[LSOF_FIX_CNTX].st && Fcntx && Lp->cntx && CntxStatus)
+        json_print_str(sep, "security_context", Lp->cntx);
+#endif
+
+    if (FieldSel[LSOF_FIX_PGID].st && Fpgid)
+        json_print_int(sep, "pgid", Lp->pgid);
+
+#if defined(HASPPID)
+    if (FieldSel[LSOF_FIX_PPID].st && Fppid)
+        json_print_int(sep, "ppid", Lp->ppid);
+#endif
+
+    if (FieldSel[LSOF_FIX_CMD].st)
+        json_print_str(sep, "command", Lp->cmd ? Lp->cmd : "(unknown)");
+
+    if (FieldSel[LSOF_FIX_UID].st)
+        json_print_int(sep, "uid", (int)Lp->uid);
+
+    if (FieldSel[LSOF_FIX_LOGIN].st) {
+        cp = printuid(ctx, (UID_ARG)Lp->uid, &ty);
+        if (ty == 0)
+            json_print_str(sep, "login", cp);
+    }
+}
+
 /*
  * print_proc() - print process
  */
@@ -1898,6 +2072,56 @@ int print_proc(struct lsof_context *ctx) {
         }
         return (0);
     }
+    /*
+     * JSON output modes — only emit on PrPass 1 (actual printing pass)
+     */
+    if ((Fjson || Fjsonl) && PrPass) {
+        for (Lf = Lp->file; Lf; Lf = Lf->next) {
+            if (is_file_sel(ctx, Lp, Lf))
+                break;
+        }
+        if (!Lf)
+            return (rv);
+        rv = 1;
+
+        if (Fjson) {
+            /* Nested JSON: process object with files array */
+            if (!Fjson_first_proc)
+                putchar(',');
+            Fjson_first_proc = 0;
+            int sep = 0;
+            putchar('{');
+            json_print_proc_fields(ctx, &sep);
+            if (sep)
+                putchar(',');
+            printf("\"files\":[");
+            int first_file = 1;
+            for (Lf = Lp->file; Lf; Lf = Lf->next) {
+                if (!is_file_sel(ctx, Lp, Lf))
+                    continue;
+                if (!first_file)
+                    putchar(',');
+                putchar('{');
+                int fsep = 0;
+                json_print_file(ctx, &fsep);
+                putchar('}');
+                first_file = 0;
+            }
+            printf("]}");
+        } else {
+            /* JSON Lines: one line per file, process fields denormalized */
+            for (Lf = Lp->file; Lf; Lf = Lf->next) {
+                if (!is_file_sel(ctx, Lp, Lf))
+                    continue;
+                int sep = 0;
+                putchar('{');
+                json_print_proc_fields(ctx, &sep);
+                json_print_file(ctx, &sep);
+                printf("}\n");
+            }
+        }
+        return (rv);
+    }
     /*
      * If fields have been selected, output the process-only ones, provided
      * that some file has also been selected.

From 5eba279198f23416f52b1b0f9cc722c248b3404b Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:25:05 +0000
Subject: [PATCH 4/8] feat: add JSON envelope wrapper for -J nested output

Emits {"lsof_version":"...","processes":[...]} around process
objects. Handles empty results and suppresses -F marker output
in JSON modes during repeat cycles.
---
 src/main.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/main.c b/src/main.c
index 199ffe1d..20e64a00 100644
--- a/src/main.c
+++ b/src/main.c
@@ -32,6 +32,7 @@
 
 #include "common.h"
 #include "cli.h"
+#include "version.h"
 
 /*
  * Local definitions
@@ -1390,6 +1391,10 @@ int main(int argc, char *argv[]) {
             (void)qsort((QSORT_P *)slp, (size_t)Nlproc,
                         (size_t)sizeof(struct lproc *), comppid);
         }
+        if (Fjson) {
+            printf("{\"lsof_version\":\"%s\",\"processes\":[", LSOF_VERSION);
+            Fjson_first_proc = 1;
+        }
         if ((n = Nlproc)) {
 
 #if defined(HASNCACHE)
@@ -1546,6 +1551,11 @@ int main(int argc, char *argv[]) {
             }
             Lf = lf;
         }
+        if (Fjson) {
+            printf("]}\n");
+        } else if (Fjsonl && RptTm) {
+            putchar('\n');
+        }
         /*
          * If a repeat time is set, sleep for the specified time.
          *
@@ -1593,7 +1603,9 @@ int main(int argc, char *argv[]) {
             }
 #endif /* defined(HAS_STRFTIME) */
 
-            if (Ffield) {
+            if (Fjson || Fjsonl) {
+                /* JSON modes handle their own cycle separation */
+            } else if (Ffield) {
                 putchar(LSOF_FID_MARK);
 
 #if defined(HAS_STRFTIME)

From f6226510f580135ffd1877a849a42aa226bf9b5b Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:27:20 +0000
Subject: [PATCH 5/8] test: add JSON and JSON Lines output test cases

---
 Makefile.am                     |  4 +-
 tests/case-30-json-output.bash  | 71 +++++++++++++++++++++++++++++++++
 tests/case-31-jsonl-output.bash | 50 +++++++++++++++++++++++
 3 files changed, 124 insertions(+), 1 deletion(-)
 create mode 100755 tests/case-30-json-output.bash
 create mode 100755 tests/case-31-jsonl-output.bash

diff --git a/Makefile.am b/Makefile.am
index fbe28fac..410c6ca3 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -132,7 +132,9 @@ DIALECT_NEUTRAL_TESTS = tests/case-00-hello.bash \
 	tests/case-20-offset-field.bash \
 	tests/case-20-repeat-count.bash \
 	tests/case-21-exit-Q-status.bash \
-	tests/case-22-empty-process-name.bash
+	tests/case-22-empty-process-name.bash \
+	tests/case-30-json-output.bash \
+	tests/case-31-jsonl-output.bash
 TESTS = $(DIALECT_NEUTRAL_TESTS)
 EXTRA_DIST += $(DIALECT_NEUTRAL_TESTS) \
 	tests/case-13-classic.bash \
diff --git a/tests/case-30-json-output.bash b/tests/case-30-json-output.bash
new file mode 100755
index 00000000..4ad075bc
--- /dev/null
+++ b/tests/case-30-json-output.bash
@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+source tests/common.bash
+
+# Skip if python3 not available (needed for JSON validation)
+if ! command -v python3 &>/dev/null; then
+    echo "SKIP: python3 not available" >> $report
+    exit 77
+fi
+
+{
+    # Test 1: -J produces valid JSON
+    output=$($lsof -J -p $$ 2>/dev/null)
+    if ! echo "$output" | python3 -m json.tool > /dev/null 2>&1; then
+        echo "FAIL: -J output is not valid JSON" >> $report
+        exit 1
+    fi
+    echo "PASS: -J produces valid JSON" >> $report
+
+    # Test 2: -J output has lsof_version and processes keys
+    echo "$output" | python3 -c "
+import sys, json
+d = json.load(sys.stdin)
+assert 'lsof_version' in d, 'missing lsof_version'
+assert 'processes' in d, 'missing processes'
+assert isinstance(d['processes'], list), 'processes is not a list'
+assert len(d['processes']) > 0, 'no processes found'
+" 2>&1 || { echo "FAIL: -J output structure invalid" >> $report; exit 1; }
+    echo "PASS: -J output structure valid" >> $report
+
+    # Test 3: -J -Fpcfn only includes selected fields
+    output_sel=$($lsof -J -Fpcfn -p $$ 2>/dev/null)
+    echo "$output_sel" | python3 -c "
+import sys, json
+d = json.load(sys.stdin)
+p = d['processes'][0]
+assert 'pid' in p, 'missing pid'
+assert 'command' in p, 'missing command'
+f = p['files'][0]
+allowed_file_keys = {'fd', 'name'}
+actual_file_keys = set(f.keys())
+extra_keys = actual_file_keys - allowed_file_keys
+assert not extra_keys, 'unexpected file keys with -Fpcfn: %s' % extra_keys
+assert 'uid' not in p, 'uid should not be present with -Fpcfn'
+" 2>&1 || { echo "FAIL: -J field selection not working" >> $report; exit 1; }
+    echo "PASS: -J field selection works" >> $report
+
+    # Test 4: -J empty result produces valid JSON
+    output_empty=$($lsof -J -p 999999 2>/dev/null)
+    echo "$output_empty" | python3 -c "
+import sys, json
+d = json.load(sys.stdin)
+assert d['processes'] == [], 'empty result should have empty processes array'
+" 2>&1 || { echo "FAIL: -J empty result is not valid JSON" >> $report; exit 1; }
+    echo "PASS: -J empty result is valid JSON" >> $report
+
+    # Test 5: -J and -j are mutually exclusive
+    if $lsof -J -j 2>/dev/null; then
+        echo "FAIL: -J -j should error" >> $report
+        exit 1
+    fi
+    echo "PASS: -J -j mutual exclusivity" >> $report
+
+    # Test 6: -J and -t are mutually exclusive
+    if $lsof -J -t 2>/dev/null; then
+        echo "FAIL: -J -t should error" >> $report
+        exit 1
+    fi
+    echo "PASS: -J -t mutual exclusivity" >> $report
+
+    exit 0
+} > $report 2>&1
diff --git a/tests/case-31-jsonl-output.bash b/tests/case-31-jsonl-output.bash
new file mode 100755
index 00000000..6a6b23c0
--- /dev/null
+++ b/tests/case-31-jsonl-output.bash
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+source tests/common.bash
+
+# Skip if python3 not available
+if ! command -v python3 &>/dev/null; then
+    echo "SKIP: python3 not available" >> $report
+    exit 77
+fi
+
+{
+    # Test 1: -j produces valid JSON Lines (each line is valid JSON)
+    tmpout=$(mktemp)
+    $lsof -j -p $$ 2>/dev/null > "$tmpout"
+    fail=0
+    while IFS= read -r line; do
+        if [ -z "$line" ]; then
+            continue
+        fi
+        if ! echo "$line" | python3 -m json.tool > /dev/null 2>&1; then
+            echo "FAIL: -j line is not valid JSON: $line" >> $report
+            fail=1
+            break
+        fi
+    done < "$tmpout"
+    rm -f "$tmpout"
+    if [ $fail -ne 0 ]; then
+        exit 1
+    fi
+    echo "PASS: -j produces valid JSON Lines" >> $report
+
+    # Test 2: -j lines contain both process and file fields (denormalized)
+    line=$($lsof -j -p $$ 2>/dev/null | head -1)
+    echo "$line" | python3 -c "
+import sys, json
+d = json.load(sys.stdin)
+assert 'pid' in d, 'missing pid'
+assert 'fd' in d or 'command' in d, 'missing file or process fields'
+" 2>&1 || { echo "FAIL: -j line missing expected fields" >> $report; exit 1; }
+    echo "PASS: -j lines have denormalized fields" >> $report
+
+    # Test 3: -j with no matching process produces empty output
+    output=$($lsof -j -p 999999 2>/dev/null)
+    if [ -n "$output" ]; then
+        echo "FAIL: -j with no matches should produce empty output" >> $report
+        exit 1
+    fi
+    echo "PASS: -j empty result is empty" >> $report
+
+    exit 0
+} > $report 2>&1

From c2e600fa88fa3cbf2c0dba4fee857915343d193a Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:27:52 +0000
Subject: [PATCH 6/8] docs: add -J/-j JSON output flags to man page

---
 Lsof.8 | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/Lsof.8 b/Lsof.8
index 51192e19..1e5fd037 100644
--- a/Lsof.8
+++ b/Lsof.8
@@ -900,6 +900,47 @@ When specified without a PGID set that's all it does.
 .B \-H
 directs lsof to print human readable sizes, e.g. 123.4K 456.7M.
 .TP \w'names'u+4
+.B \-J
+selects JSON output mode.  Instead of the traditional tabular or
+.B \-F
+field output, lsof produces a single JSON object on stdout containing
+a
+.B "processes"
+array.  Each process object contains its fields and a
+.B "files"
+array of open file entries.
+.IP
+Field selection follows the same rules as
+.BR \-F :
+use
+.B \-F
+with field characters to select which fields appear in the JSON output.
+Without
+.BR \-F ,
+the default field set is used.
+.IP
+.B \-J
+is mutually exclusive with
+.B \-j
+and
+.BR \-t .
+Warnings and errors are sent to stderr; stdout is always valid JSON.
+.TP \w'names'u+4
+.B \-j
+selects JSON Lines output mode.  Each open file produces one JSON
+object per line, combining process and file fields in a single
+denormalized record.  This format is suitable for streaming pipelines,
+log ingestion (Splunk, Datadog, Elastic), and line\-oriented tools.
+.IP
+Field selection follows the same rules as
+.BR \-J .
+.IP
+.B \-j
+is mutually exclusive with
+.B \-J
+and
+.BR \-t .
+.TP \w'names'u+4
 .BI \-i " [i]"
 selects the listing of files any of whose Internet address
 matches the address specified in \fIi\fP.

From 34d6b1b4889221ec4ba0bf88168c8ac608eaff77 Mon Sep 17 00:00:00 2001
From: kurok <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 12:46:58 +0000
Subject: [PATCH 7/8] fix: move JSON envelope to print.c, add version.h build
 deps

Refactors json_open_envelope/json_close_envelope into print.c
which already includes version.h via the correct build ordering.
Updates all dialect Makefiles to add version.h as a dependency
for print.o.
---
 lib/dialects/aix/Makefile        |  2 +-
 lib/dialects/darwin/Makefile     |  2 +-
 lib/dialects/freebsd/Makefile    |  2 +-
 lib/dialects/hpux/kmem/Makefile  |  2 +-
 lib/dialects/hpux/pstat/Makefile |  2 +-
 lib/dialects/linux/Makefile      |  2 +-
 lib/dialects/netbsd/Makefile     |  2 +-
 lib/dialects/openbsd/Makefile    |  2 +-
 lib/dialects/osr/Makefile        |  2 +-
 lib/dialects/sun/Makefile        |  2 +-
 lib/dialects/uw/Makefile         |  2 +-
 lib/proto.h                      |  2 ++
 src/main.c                       |  6 ++----
 src/print.c                      | 16 ++++++++++++++++
 14 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/lib/dialects/aix/Makefile b/lib/dialects/aix/Makefile
index 980e78f8..00a57915 100644
--- a/lib/dialects/aix/Makefile
+++ b/lib/dialects/aix/Makefile
@@ -155,7 +155,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/darwin/Makefile b/lib/dialects/darwin/Makefile
index 81fab7eb..e7ababc0 100644
--- a/lib/dialects/darwin/Makefile
+++ b/lib/dialects/darwin/Makefile
@@ -162,7 +162,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/freebsd/Makefile b/lib/dialects/freebsd/Makefile
index 33c0aaec..e1e40b18 100644
--- a/lib/dialects/freebsd/Makefile
+++ b/lib/dialects/freebsd/Makefile
@@ -141,7 +141,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/hpux/kmem/Makefile b/lib/dialects/hpux/kmem/Makefile
index 080063da..d159227f 100644
--- a/lib/dialects/hpux/kmem/Makefile
+++ b/lib/dialects/hpux/kmem/Makefile
@@ -147,7 +147,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/hpux/pstat/Makefile b/lib/dialects/hpux/pstat/Makefile
index 9eace673..f30140e1 100644
--- a/lib/dialects/hpux/pstat/Makefile
+++ b/lib/dialects/hpux/pstat/Makefile
@@ -136,7 +136,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/linux/Makefile b/lib/dialects/linux/Makefile
index f8adaa60..cbfefebf 100644
--- a/lib/dialects/linux/Makefile
+++ b/lib/dialects/linux/Makefile
@@ -167,7 +167,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/netbsd/Makefile b/lib/dialects/netbsd/Makefile
index 602673f2..c62f67e5 100644
--- a/lib/dialects/netbsd/Makefile
+++ b/lib/dialects/netbsd/Makefile
@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/openbsd/Makefile b/lib/dialects/openbsd/Makefile
index 5b566fc0..36ee75c1 100644
--- a/lib/dialects/openbsd/Makefile
+++ b/lib/dialects/openbsd/Makefile
@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/osr/Makefile b/lib/dialects/osr/Makefile
index 79c38dfd..1b3e1f02 100644
--- a/lib/dialects/osr/Makefile
+++ b/lib/dialects/osr/Makefile
@@ -151,7 +151,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/sun/Makefile b/lib/dialects/sun/Makefile
index c3e0cd4b..449947bc 100644
--- a/lib/dialects/sun/Makefile
+++ b/lib/dialects/sun/Makefile
@@ -146,7 +146,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/dialects/uw/Makefile b/lib/dialects/uw/Makefile
index cf9f38e6..c5fdb1a5 100644
--- a/lib/dialects/uw/Makefile
+++ b/lib/dialects/uw/Makefile
@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 
diff --git a/lib/proto.h b/lib/proto.h
index 2caceb80..2d28a90c 100644
--- a/lib/proto.h
+++ b/lib/proto.h
@@ -187,6 +187,8 @@ extern void print_init(struct lsof_context *ctx);
 extern void printname(struct lsof_context *ctx, int nl);
 extern char *print_kptr(KA_T kp, char *buf, size_t bufl);
 extern int print_proc(struct lsof_context *ctx);
+extern void json_open_envelope(void);
+extern void json_close_envelope(void);
 extern void fd_to_string(enum lsof_fd_type fd_type, int fd_num, char *buf);
 extern void printrawaddr(struct lsof_context *ctx, struct sockaddr *sa);
 extern void print_tcptpi(struct lsof_context *ctx, int nl);
diff --git a/src/main.c b/src/main.c
index 20e64a00..cbba9ff7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -32,7 +32,6 @@
 
 #include "common.h"
 #include "cli.h"
-#include "version.h"
 
 /*
  * Local definitions
@@ -1392,8 +1391,7 @@ int main(int argc, char *argv[]) {
                         (size_t)sizeof(struct lproc *), comppid);
         }
         if (Fjson) {
-            printf("{\"lsof_version\":\"%s\",\"processes\":[", LSOF_VERSION);
-            Fjson_first_proc = 1;
+            json_open_envelope();
         }
         if ((n = Nlproc)) {
 
@@ -1552,7 +1550,7 @@ int main(int argc, char *argv[]) {
             Lf = lf;
         }
         if (Fjson) {
-            printf("]}\n");
+            json_close_envelope();
         } else if (Fjsonl && RptTm) {
             putchar('\n');
         }
diff --git a/src/print.c b/src/print.c
index 29ca3ad5..bdf2321d 100644
--- a/src/print.c
+++ b/src/print.c
@@ -31,6 +31,7 @@
 #include "common.h"
 #include "cli.h"
 #include "proto.h"
+#include "version.h"
 #include <inttypes.h>
 
 /*
@@ -1865,6 +1866,21 @@ int human_readable_size(SZOFFTYPE sz, int print, int col) {
     return strlen(buf);
 }
 
+/*
+ * json_open_envelope() - emit JSON opening envelope for -J mode
+ */
+void json_open_envelope(void) {
+    printf("{\"lsof_version\":\"%s\",\"processes\":[", LSOF_VERSION);
+    Fjson_first_proc = 1;
+}
+
+/*
+ * json_close_envelope() - emit JSON closing envelope for -J mode
+ */
+void json_close_envelope(void) {
+    printf("]}\n");
+}
+
 /*
  * json_print_file() - print a single file entry as JSON fields
  */

From bb8bab1e26ab1c8548be773307c9a90333f295e3 Mon Sep 17 00:00:00 2001
From: YuriyRyabikov <22548029+kurok@users.noreply.github.com>
Date: Thu, 12 Mar 2026 14:17:39 +0000
Subject: [PATCH 8/8] refactor: address code review feedback

- Extract select_default_fields() to deduplicate field selection logic
  shared between -F and -J/-j default handling (jiegec review)
- Escape JSON keys via json_print_key() helper (jiegec review)
- Add json_print_char() for single-char fields like access and lock,
  avoiding unnecessary char[2] array construction (jiegec review)
---
 src/main.c  | 136 +++++++++++++++++++++-------------------------------
 src/print.c |  66 +++++++++++++++----------
 2 files changed, 96 insertions(+), 106 deletions(-)

diff --git a/src/main.c b/src/main.c
index cbba9ff7..bfcc714b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -47,6 +47,58 @@ static int GetOpt(struct lsof_context *ctx, int ct, char *opt[], char *rules,
                   int *err);
 static char *sv_fmt_str(struct lsof_context *ctx, char *f);
 
+/*
+ * select_default_fields() - enable the default set of FieldSel entries
+ *
+ * Shared by -F (with no field chars) and -J/-j (when no -F given).
+ */
+static void select_default_fields(void) {
+    int i;
+    for (i = 0; FieldSel[i].nm; i++) {
+
+#if !defined(HASPPID)
+        if (FieldSel[i].id == LSOF_FID_PPID)
+            continue;
+#endif /* !defined(HASPPID) */
+
+#if !defined(HASTASKS)
+        if (FieldSel[i].id == LSOF_FID_TCMD)
+            continue;
+#endif /* !defined(HASTASKS) */
+
+#if !defined(HASFSTRUCT)
+        if (FieldSel[i].id == LSOF_FID_CT || FieldSel[i].id == LSOF_FID_FA ||
+            FieldSel[i].id == LSOF_FID_FG || FieldSel[i].id == LSOF_FID_NI)
+            continue;
+#endif /* !defined(HASFSTRUCT) */
+
+#if defined(HASSELINUX)
+        if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
+            continue;
+#else  /* !defined(HASSELINUX) */
+        if (FieldSel[i].id == LSOF_FID_CNTX)
+            continue;
+#endif /* !defined(HASSELINUX) */
+
+        if (FieldSel[i].id == LSOF_FID_RDEV)
+            continue; /* for compatibility */
+
+#if !defined(HASTASKS)
+        if (FieldSel[i].id == LSOF_FID_TID)
+            continue;
+#endif /* !defined(HASTASKS) */
+
+#if !defined(HASZONES)
+        if (FieldSel[i].id == LSOF_FID_ZONE)
+            continue;
+#endif /* !defined(HASZONES) */
+
+        FieldSel[i].st = 1;
+        if (FieldSel[i].opt && FieldSel[i].ov)
+            *(FieldSel[i].opt) |= FieldSel[i].ov;
+    }
+}
+
 /*
  * main() - main function for lsof
  */
@@ -429,51 +481,7 @@ int main(int argc, char *argv[]) {
                     } else if (*GOv == '0')
                         Terminator = '\0';
                 }
-                for (i = 0; FieldSel[i].nm; i++) {
-
-#if !defined(HASPPID)
-                    if (FieldSel[i].id == LSOF_FID_PPID)
-                        continue;
-#endif /* !defined(HASPPID) */
-
-#if !defined(HASTASKS)
-                    if (FieldSel[i].id == LSOF_FID_TCMD)
-                        continue;
-#endif /* !defined(HASTASKS) */
-
-#if !defined(HASFSTRUCT)
-                    if (FieldSel[i].id == LSOF_FID_CT ||
-                        FieldSel[i].id == LSOF_FID_FA ||
-                        FieldSel[i].id == LSOF_FID_FG ||
-                        FieldSel[i].id == LSOF_FID_NI)
-                        continue;
-#endif /* !defined(HASFSTRUCT) */
-
-#if defined(HASSELINUX)
-                    if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
-                        continue;
-#else  /* !defined(HASSELINUX) */
-                    if (FieldSel[i].id == LSOF_FID_CNTX)
-                        continue;
-#endif /* !defined(HASSELINUX) */
-
-                    if (FieldSel[i].id == LSOF_FID_RDEV)
-                        continue; /* for compatibility */
-
-#if !defined(HASTASKS)
-                    if (FieldSel[i].id == LSOF_FID_TID)
-                        continue;
-#endif /* !defined(HASTASKS) */
-
-#if !defined(HASZONES)
-                    if (FieldSel[i].id == LSOF_FID_ZONE)
-                        continue;
-#endif /* !defined(HASZONES) */
-
-                    FieldSel[i].st = 1;
-                    if (FieldSel[i].opt && FieldSel[i].ov)
-                        *(FieldSel[i].opt) |= FieldSel[i].ov;
-                }
+                select_default_fields();
 
 #if defined(HASFSTRUCT)
                 Ffield = FsvFlagX = 1;
@@ -1166,42 +1174,8 @@ int main(int argc, char *argv[]) {
                 break;
             }
         }
-        if (!has_fields) {
-            for (i = 0; FieldSel[i].nm; i++) {
-#if !defined(HASPPID)
-                if (FieldSel[i].id == LSOF_FID_PPID)
-                    continue;
-#endif
-#if !defined(HASTASKS)
-                if (FieldSel[i].id == LSOF_FID_TCMD ||
-                    FieldSel[i].id == LSOF_FID_TID)
-                    continue;
-#endif
-#if !defined(HASFSTRUCT)
-                if (FieldSel[i].id == LSOF_FID_CT ||
-                    FieldSel[i].id == LSOF_FID_FA ||
-                    FieldSel[i].id == LSOF_FID_FG ||
-                    FieldSel[i].id == LSOF_FID_NI)
-                    continue;
-#endif
-#if defined(HASSELINUX)
-                if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
-                    continue;
-#else
-                if (FieldSel[i].id == LSOF_FID_CNTX)
-                    continue;
-#endif
-                if (FieldSel[i].id == LSOF_FID_RDEV)
-                    continue;
-#if !defined(HASZONES)
-                if (FieldSel[i].id == LSOF_FID_ZONE)
-                    continue;
-#endif
-                FieldSel[i].st = 1;
-                if (FieldSel[i].opt && FieldSel[i].ov)
-                    *(FieldSel[i].opt) |= FieldSel[i].ov;
-            }
-        }
+        if (!has_fields)
+            select_default_fields();
     }
 
     if (DChelp || err || Fhelp || fh || version)
diff --git a/src/print.c b/src/print.c
index bdf2321d..351ef574 100644
--- a/src/print.c
+++ b/src/print.c
@@ -135,41 +135,57 @@ static void json_puts_escaped(const char *s) {
     }
 }
 
-static void json_print_str(int *sep, const char *key, const char *val) {
+/*
+ * json_print_key() - print comma separator and escaped JSON key
+ */
+static void json_print_key(int *sep, const char *key) {
     if (*sep)
         putchar(',');
-    printf("\"%s\":\"", key);
-    json_puts_escaped(val);
     putchar('"');
+    json_puts_escaped(key);
+    printf("\":");
     *sep = 1;
 }
 
+static void json_print_str(int *sep, const char *key, const char *val) {
+    json_print_key(sep, key);
+    putchar('"');
+    json_puts_escaped(val);
+    putchar('"');
+}
+
+static void json_print_char(int *sep, const char *key, char val) {
+    json_print_key(sep, key);
+    putchar('"');
+    if (val == '"')
+        fputs("\\\"", stdout);
+    else if (val == '\\')
+        fputs("\\\\", stdout);
+    else if (val < 0x20)
+        printf("\\u%04x", (unsigned int)(unsigned char)val);
+    else
+        putchar(val);
+    putchar('"');
+}
+
 static void json_print_int(int *sep, const char *key, int val) {
-    if (*sep)
-        putchar(',');
-    printf("\"%s\":%d", key, val);
-    *sep = 1;
+    json_print_key(sep, key);
+    printf("%d", val);
 }
 
 static void json_print_uint64_str(int *sep, const char *key, uint64_t val) {
-    if (*sep)
-        putchar(',');
-    printf("\"%s\":\"%" PRIu64 "\"", key, val);
-    *sep = 1;
+    json_print_key(sep, key);
+    printf("\"%" PRIu64 "\"", val);
 }
 
 static void json_print_long(int *sep, const char *key, long val) {
-    if (*sep)
-        putchar(',');
-    printf("\"%s\":%ld", key, val);
-    *sep = 1;
+    json_print_key(sep, key);
+    printf("%ld", val);
 }
 
 static void json_print_ulong(int *sep, const char *key, unsigned long val) {
-    if (*sep)
-        putchar(',');
-    printf("\"%s\":%lu", key, val);
-    *sep = 1;
+    json_print_key(sep, key);
+    printf("%lu", val);
 }
 
 #if !defined(HASNORPC_H)
@@ -1902,14 +1918,14 @@ static void json_print_file(struct lsof_context *ctx, int *sep) {
         }
     }
     if (FieldSel[LSOF_FIX_ACCESS].st) {
-        char a[2] = {access_to_char(Lf->access), '\0'};
-        if (a[0] != ' ')
-            json_print_str(sep, "access", a);
+        char a = access_to_char(Lf->access);
+        if (a != ' ')
+            json_print_char(sep, "access", a);
     }
     if (FieldSel[LSOF_FIX_LOCK].st) {
-        char l[2] = {lock_to_char(Lf->lock), '\0'};
-        if (l[0] != ' ')
-            json_print_str(sep, "lock", l);
+        char l = lock_to_char(Lf->lock);
+        if (l != ' ')
+            json_print_char(sep, "lock", l);
     }
     if (FieldSel[LSOF_FIX_TYPE].st && Lf->type != LSOF_FILE_NONE) {
         file_type_to_string(Lf->type, Lf->unknown_file_type_number, type,