watch: compat: use stderr to determine screen dimensions

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/procps/watch.c b/procps/watch.c
index ad44b3a3e2d6e4999022c8656c8bbfd8989cd16a..126945c40b243cdee7db2238d71222c6407def67 100644 (file)
--- a/procps/watch.c
+++ b/procps/watch.c
@@ -32,13 +32,19 @@ int watch_main(int argc UNUSED_PARAM, char **argv)
        char *header;
        char *cmd;
 
+#if 0 // maybe ENABLE_DESKTOP?
+       // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
+       close(STDIN_FILENO);
+       xopen("/dev/null", O_RDONLY);
+#endif
+
        opt_complementary = "-1:n+"; // at least one param; -n NUM
        // "+": stop at first non-option (procps 3.x only)
        opt = getopt32(argv, "+dtn:", &period);
        argv += optind;
 
        // watch from both procps 2.x and 3.x does concatenation. Example:
-       // watch ls -l "a /tmp" "2>&1" -- ls won't see "a /tmp" as one param
+       // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
        cmd = *argv;
        while (*++argv)
                cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
@@ -51,7 +57,9 @@ int watch_main(int argc UNUSED_PARAM, char **argv)
                        const unsigned time_len = sizeof("1234-67-90 23:56:89");
                        time_t t;
 
-                       get_terminal_width_height(STDIN_FILENO, &new_width, NULL);
+                       // STDERR_FILENO is procps3 compat:
+                       // "watch ls 2>/dev/null" does not detect tty size
+                       get_terminal_width_height(STDERR_FILENO, &new_width, NULL);
                        if (new_width != width) {
                                width = new_width;
                                free(header);
@@ -62,7 +70,8 @@ int watch_main(int argc UNUSED_PARAM, char **argv)
                                strftime(header + width - time_len, time_len,
                                        "%Y-%m-%d %H:%M:%S", localtime(&t));
 
-                       printf("%s\n\n", header); /* compat: empty line */
+                       // compat: empty line between header and cmd output
+                       printf("%s\n\n", header);
                }
                fflush_all();
                // TODO: 'real' watch pipes cmd's output to itself