ash,hush: make trap output short signal names, without SIG prefix

function                                             old     new   delta
evalvar                                             1373    1371      -2
builtin_trap                                         457     441     -16
trapcmd                                              260     236     -24

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash.c b/shell/ash.c
index c909cae..d7355ce 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -12267,13 +12267,16 @@
 		for (signo = 0; signo < NSIG; signo++) {
 			char *tr = trap_ptr[signo];
 			if (tr) {
-				out1fmt("trap -- %s %s%s\n",
+				/* note: bash adds "SIG", but only if invoked
+				 * as "bash". If called as "sh", or if set -o posix,
+				 * then it prints short signal names.
+				 * We are printing short names: */
+				out1fmt("trap -- %s %s\n",
 						single_quote(tr),
-						(signo == 0 ? "" : "SIG"),
 						get_signame(signo));
 		/* trap_ptr != trap only if we are in special-cased `trap` code.
 		 * In this case, we will exit very soon, no need to free(). */
-				/* if (trap_ptr != trap) */
+				/* if (trap_ptr != trap && tp[0]) */
 				/*	free(tr); */
 			}
 		}
diff --git a/shell/ash_test/ash-signals/savetrap.right b/shell/ash_test/ash-signals/savetrap.right
index 9cfd7a5..a59225b 100644
--- a/shell/ash_test/ash-signals/savetrap.right
+++ b/shell/ash_test/ash-signals/savetrap.right
@@ -1,8 +1,8 @@
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 Done
 Exiting
diff --git a/shell/ash_test/ash-signals/signal1.right b/shell/ash_test/ash-signals/signal1.right
index beb0a98..cf403ac 100644
--- a/shell/ash_test/ash-signals/signal1.right
+++ b/shell/ash_test/ash-signals/signal1.right
@@ -1,20 +1,20 @@
 got signal
-trap -- 'echo got signal' SIGUSR1
+trap -- 'echo got signal' USR1
 sent 1 signal
 got signal
 wait interrupted
-trap -- 'echo got signal' SIGUSR1
+trap -- 'echo got signal' USR1
 sent 2 signal
 got signal
 wait interrupted
-trap -- 'echo got signal' SIGUSR1
+trap -- 'echo got signal' USR1
 sent 3 signal
 got signal
 wait interrupted
-trap -- 'echo got signal' SIGUSR1
+trap -- 'echo got signal' USR1
 sent 4 signal
 got signal
 wait interrupted
-trap -- 'echo got signal' SIGUSR1
+trap -- 'echo got signal' USR1
 sent 5 signal
 sleep completed
diff --git a/shell/hush.c b/shell/hush.c
index d75b0da..b515eab 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -7111,8 +7111,11 @@
 			if (G.traps[i]) {
 				printf("trap -- ");
 				print_escaped(G.traps[i]);
-				/* bash compat: it says SIGxxx, not just xxx */
-				printf(" %s%s\n", i == 0 ? "" : "SIG", get_signame(i));
+				/* note: bash adds "SIG", but only if invoked
+				 * as "bash". If called as "sh", or if set -o posix,
+				 * then it prints short signal names.
+				 * We are printing short names: */
+				printf(" %s\n", get_signame(i));
 			}
 		}
 		/*fflush(stdout); - done after each builtin anyway */
diff --git a/shell/hush_test/hush-trap/savetrap.right b/shell/hush_test/hush-trap/savetrap.right
index 9cfd7a5..a59225b 100644
--- a/shell/hush_test/hush-trap/savetrap.right
+++ b/shell/hush_test/hush-trap/savetrap.right
@@ -1,8 +1,8 @@
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 trap -- 'echo Exiting' EXIT
-trap -- 'echo WINCH!' SIGWINCH
+trap -- 'echo WINCH!' WINCH
 Done
 Exiting
diff --git a/shell/hush_test/hush-trap/usage.right b/shell/hush_test/hush-trap/usage.right
index 5b90222..c0dbd6c 100644
--- a/shell/hush_test/hush-trap/usage.right
+++ b/shell/hush_test/hush-trap/usage.right
@@ -2,13 +2,13 @@
 ___
 ___
 trap -- 'a' EXIT
-trap -- 'a' SIGINT
-trap -- 'a' SIGUSR1
-trap -- 'a' SIGUSR2
+trap -- 'a' INT
+trap -- 'a' USR1
+trap -- 'a' USR2
 ___
 ___
-trap -- 'a' SIGUSR1
-trap -- 'a' SIGUSR2
+trap -- 'a' USR1
+trap -- 'a' USR2
 ___
 ___
-trap -- 'a' SIGUSR2
+trap -- 'a' USR2