document trap ... EXIT

Fixes #1180

doc_src/trap.txt

@@ -2,7 +2,7 @@
 
 \subsection trap-synopsis Synopsis
 \fish{synopsis}
-trap [OPTIONS] [[ARG] SIGSPEC ... ]
+trap [OPTIONS] [[ARG] REASON ... ]
 \endfish
 
 \subsection trap-description Description
@@ -13,25 +13,25 @@ The following parameters are available:
 
 - `ARG` is the command to be executed on signal delivery.
 
-- `SIGSPEC` is the name of the signal to trap.
+- `REASON` is the name of the event to trap. For example, a signal like `INT` or `SIGINT`, or the special symbol `EXIT`.
 
 - `-l` or `--list-signals` prints a list of signal names.
 
 - `-p` or `--print` prints all defined signal handlers.
 
-If `ARG` and `SIGSPEC` are both specified, `ARG` is the command to be executed when the signal specified by `SIGSPEC` is delivered.
+If `ARG` and `REASON` are both specified, `ARG` is the command to be executed when the event specified by `REASON` occurs (e.g., the signal is delivered).
 
-If `ARG` is absent (and there is a single SIGSPEC) or -, each specified signal is reset to its original disposition (the value it had upon entrance to the shell).  If `ARG` is the null string the signal specified by each `SIGSPEC` is ignored by the shell and by the commands it invokes.
+If `ARG` is absent (and there is a single REASON) or -, each specified signal is reset to its original disposition (the value it had upon entrance to the shell).  If `ARG` is the null string the signal specified by each `REASON` is ignored by the shell and by the commands it invokes.
 
-If `ARG` is not present and `-p` has been supplied, then the trap commands associated with each `SIGSPEC` are displayed. If no arguments are supplied or if only `-p` is given, `trap` prints the list of commands associated with each signal.
+If `ARG` is not present and `-p` has been supplied, then the trap commands associated with each `REASON` are displayed. If no arguments are supplied or if only `-p` is given, `trap` prints the list of commands associated with each signal.
 
 Signal names are case insensitive and the `SIG` prefix is optional.
 
-The return status is 1 if any `SIGSPEC` is invalid; otherwise trap returns 0.
+The return status is 1 if any `REASON` is invalid; otherwise trap returns 0.
 
 \subsection trap-example Example
 
 \fish
 trap "status --print-stack-trace" SIGUSR1
 # Prints a stack trace each time the SIGUSR1 signal is sent to the shell.
-\endfish
+\endfish

share/functions/trap.fish

@@ -1,3 +1,4 @@
+# This defines a compatibility shim for the `trap` command found in other shells like bash and zsh.
 
 function __trap_translate_signal
     set upper (echo $argv[1]|tr a-z A-Z)
@@ -5,15 +6,13 @@ function __trap_translate_signal
 end
 
 function __trap_switch
-
     switch $argv[1]
-        case EXIT
+        case EXIT exit
             echo --on-process-exit %self
 
         case '*'
             echo --on-signal $argv[1]
     end
-
 end
 
 function trap -d 'Perform an action when the shell receives a signal'
@@ -103,12 +102,11 @@ function trap -d 'Perform an action when the shell receives a signal'
             set -e opt[1]
 
             for i in $opt
-
                 set -l sig (__trap_translate_signal $i)
                 set sw (__trap_switch $sig)
 
                 if test $sig
-                    eval "function __trap_handler_$sig $sw; $cmd; end"
+                    echo "function __trap_handler_$sig $sw; $cmd; end" | source
                 else
                     return 1
                 end