kill (-l/-L): print one signal per line when stdout is not a TTY

It helps using kill -l/-L in a script.

    $ ./kill -L
     1 HUP      2 INT      3 QUIT     4 ILL      5 TRAP
     6 ABRT     6 IOT      7 BUS      8 FPE      9 KILL
     ...
    $ ./kill -L | cat
    1 HUP
    2 INT
    3 QUIT
    ...

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

diff --git a/misc-utils/kill.c b/misc-utils/kill.c
index 7ffcee6327ae3cbf729163788296ab5b8f711a79..b522bcb2088724e8f0d9a2d5c7a9707baa174d6a 100644 (file)
--- a/misc-utils/kill.c
+++ b/misc-utils/kill.c
@@ -192,6 +192,11 @@ static void print_process_signal_state(pid_t pid)
        ul_unref_path(pc);
 }
 
+static void print_signal_number_and_name(FILE *fp, int signum, const char *name, bool newline)
+{
+       fprintf(fp, "%2d %-8s%s", signum, name, newline? "\n": "");
+}
+
 static void pretty_print_signal(FILE *fp, size_t term_width, size_t *lpos,
                                int signum, const char *name)
 {
@@ -200,17 +205,22 @@ static void pretty_print_signal(FILE *fp, size_t term_width, size_t *lpos,
                *lpos = 0;
        }
        *lpos += KILL_FIELD_WIDTH;
-       fprintf(fp, "%2d %-8s", signum, name);
+       print_signal_number_and_name(fp, signum, name, false);
 }
 
 static void print_all_signals(FILE *fp, int with_signum)
 {
-       size_t n, lth, lpos = 0, width;
+       size_t n, lth, lpos = 0;
        const char *signame = NULL;
        int signum = 0;
+       int pretty = isatty(STDOUT_FILENO);
 
        if (!with_signum) {
                for (n = 0; get_signame_by_idx(n, &signame, NULL) == 0; n++) {
+                       if (!pretty) {
+                               fprintf(fp, "%s\n", signame);
+                               continue;
+                       }
                        lth = 1 + strlen(signame);
                        if (KILL_OUTPUT_WIDTH < lpos + lth) {
                                fputc('\n', fp);
@@ -221,21 +231,33 @@ static void print_all_signals(FILE *fp, int with_signum)
                        fputs(signame, fp);
                }
 #ifdef SIGRTMIN
-               fputs(" RT<N> RTMIN+<N> RTMAX-<N>", fp);
+               if (!pretty)
+                       fputs("RT<N>\nRTMIN+<N>\nRTMAX-<N>", fp);
+               else
+                       fputs(" RT<N> RTMIN+<N> RTMAX-<N>", fp);
 #endif
                fputc('\n', fp);
                return;
        }
 
        /* with signal numbers */
-       width = get_terminal_width(KILL_OUTPUT_WIDTH + 1) - 1;
-       for (n = 0; get_signame_by_idx(n, &signame, &signum) == 0; n++)
-               pretty_print_signal(fp, width, &lpos, signum, signame);
+       if (!pretty) {
+               for (n = 0; get_signame_by_idx(n, &signame, &signum) == 0; n++)
+                       print_signal_number_and_name(fp, signum, signame, true);
 #ifdef SIGRTMIN
-       pretty_print_signal(fp, width, &lpos, SIGRTMIN, "RTMIN");
-       pretty_print_signal(fp, width, &lpos, SIGRTMAX, "RTMAX");
+               print_signal_number_and_name(fp, SIGRTMIN, "RTMIN", true);
+               print_signal_number_and_name(fp, SIGRTMAX, "RTMAX", true);
 #endif
-       fputc('\n', fp);
+       } else {
+               size_t width = get_terminal_width(KILL_OUTPUT_WIDTH + 1) - 1;
+               for (n = 0; get_signame_by_idx(n, &signame, &signum) == 0; n++)
+                       pretty_print_signal(fp, width, &lpos, signum, signame);
+#ifdef SIGRTMIN
+               pretty_print_signal(fp, width, &lpos, SIGRTMIN, "RTMIN");
+               pretty_print_signal(fp, width, &lpos, SIGRTMAX, "RTMAX");
+#endif
+               fputc('\n', fp);
+       }
 }
 
 static void err_nosig(char *name)