Add $fish_kill_signal to track the signal that terminated a command.

Set to `0` if the command exited normally.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Notable improvements and fixes
 - `fish --no-execute` will no longer complain about unknown commands or non-matching wildcards, as these could be defined differently at runtime (especially for functions). #977
 - `jobs --quiet PID` will no longer print 'no suitable job' if the job for PID does not exist (e.g. because it has finished). #6809
+- A variable `fish_kill_signal` will be set to the signal that terminated the last command, or `0` if the command exited normally.
 
 ### Syntax changes and new commands
 

doc_src/index.rst

@@ -1059,6 +1059,8 @@ The user can change the settings of ``fish`` by changing the values of certain v
 
 - ``pipestatus``, a list of exit statuses of all processes that made up the last executed pipe.
 
+- ``fish_kill_signal``, the signal that terminated the previous command, or `0` if the command exited normally.
+
 - ``USER``, the current username. This variable can be changed by the user.
 
 - ``CMD_DURATION``, the runtime of the last command in milliseconds.

src/env.cpp

@@ -93,6 +93,7 @@ static const electric_var_t electric_variables[] = {
     {L"_", electric_var_t::freadonly},
     {L"fish_private_mode", electric_var_t::freadonly},
     {L"umask", electric_var_t::fcomputed},
+    {L"fish_kill_signal", electric_var_t::freadonly | electric_var_t::fcomputed},
 };
 
 const electric_var_t *electric_var_t::for_name(const wcstring &name) {
@@ -685,6 +686,9 @@ maybe_t<env_var_t> env_scoped_impl_t::try_get_computed(const wcstring &key) cons
     } else if (key == L"status") {
         const auto &js = perproc_data().statuses;
         return env_var_t(L"status", to_string(js.status));
+    } else if (key == L"fish_kill_signal") {
+        const auto &js = perproc_data().statuses;
+        return env_var_t(L"fish_kill_signal", to_string(js.kill_signal));
     } else if (key == L"umask") {
         // note umask() is an absurd API: you call it to set the value and it returns the old
         // value. Thus we have to call it twice, to reset the value. The env_lock protects

src/env.h

@@ -63,6 +63,10 @@ struct statuses_t {
     /// Status of the last job to exit.
     int status{0};
 
+    /// Signal from the most recent process in the last job that was terminated by a signal.
+    /// 0 if all processes exited normally.
+    int kill_signal{0};
+
     /// Pipestatus value.
     std::vector<int> pipestatus{};
 

src/proc.cpp

@@ -187,7 +187,11 @@ statuses_t job_t::get_statuses() const {
     statuses_t st{};
     st.pipestatus.reserve(processes.size());
     for (const auto &p : processes) {
-        st.pipestatus.push_back(p->status.status_value());
+        auto status = p->status;
+        if (status.signal_exited()) {
+            st.kill_signal = status.signal_code();
+        }
+        st.pipestatus.push_back(status.status_value());
     }
     int laststatus = st.pipestatus.back();
     st.status = flags().negate ? !laststatus : laststatus;

tests/signals.expect

@@ -12,6 +12,22 @@ send_line read
 expect -re "\\r\\n?read> $"
 exec -- kill -INT $pid
 expect "fish_postexec spotted"
+expect_prompt
+
+# Verify that the fish_kill_signal is set.
+send_line "functions -e postexec; function postexec --on-event fish_postexec; echo fish_kill_signal \$fish_kill_signal; end"
+expect_prompt
+send_line "sleep 5"
+sleep 0.100
+exec -- pkill -INT sleep -P $pid
+expect "fish_kill_signal 2"
+expect_prompt
+
+send_line "sleep 5"
+sleep 0.100
+exec -- pkill -TERM sleep -P $pid
+expect "fish_kill_signal 15"
+expect_prompt
 
 # Verify that sending SIGHUP to the shell, such as will happen when the tty is
 # closed by the terminal, terminates the shell and the foreground command and