diff --git a/cmd-if-shell.c b/cmd-if-shell.c
index ab69e8b5..e0e2c230 100644
--- a/cmd-if-shell.c
+++ b/cmd-if-shell.c
@@ -36,8 +36,8 @@ void	cmd_if_shell_free(void *);
 
 const struct cmd_entry cmd_if_shell_entry = {
 	"if-shell", "if",
-	"", 2, 3,
-	"shell-command command [command]",
+	"t:", 2, 3,
+	CMD_TARGET_PANE_USAGE " shell-command command [command]",
 	0,
 	NULL,
 	NULL,
@@ -55,7 +55,22 @@ cmd_if_shell_exec(struct cmd *self, struct cmd_ctx *ctx)
 {
 	struct args			*args = self->args;
 	struct cmd_if_shell_data	*cdata;
-	const char			*shellcmd = args->argv[0];
+	char				*shellcmd;
+	struct session			*s;
+	struct winlink			*wl;
+	struct window_pane		*wp;
+	struct format_tree		*ft;
+
+	wl = cmd_find_pane(ctx, args_get(args, 't'), &s, &wp);
+	if (wl == NULL)
+		return (CMD_RETURN_ERROR);
+
+	ft = format_create();
+	format_session(ft, s);
+	format_winlink(ft, s, wl);
+	format_window_pane(ft, wp);
+	shellcmd = format_expand(ft, args->argv[0]);
+	format_free(ft);
 
 	cdata = xmalloc(sizeof *cdata);
 	cdata->cmd_if = xstrdup(args->argv[1]);
@@ -68,6 +83,7 @@ cmd_if_shell_exec(struct cmd *self, struct cmd_ctx *ctx)
 	cmd_ref_ctx(ctx);
 
 	job_run(shellcmd, cmd_if_shell_callback, cmd_if_shell_free, cdata);
+	free(shellcmd);
 
 	return (CMD_RETURN_YIELD);	/* don't let client exit */
 }
diff --git a/cmd-run-shell.c b/cmd-run-shell.c
index 0d19a8e6..3942fa11 100644
--- a/cmd-run-shell.c
+++ b/cmd-run-shell.c
@@ -75,14 +75,25 @@ cmd_run_shell_exec(struct cmd *self, struct cmd_ctx *ctx)
 {
 	struct args			*args = self->args;
 	struct cmd_run_shell_data	*cdata;
-	const char			*shellcmd = args->argv[0];
+	char				*shellcmd;
+	struct session			*s;
+	struct winlink			*wl;
 	struct window_pane		*wp;
+	struct format_tree		*ft;
 
-	if (cmd_find_pane(ctx, args_get(args, 't'), NULL, &wp) == NULL)
+	wl = cmd_find_pane(ctx, args_get(args, 't'), &s, &wp);
+	if (wl == NULL)
 		return (CMD_RETURN_ERROR);
 
+	ft = format_create();
+	format_session(ft, s);
+	format_winlink(ft, s, wl);
+	format_window_pane(ft, wp);
+	shellcmd = format_expand(ft, args->argv[0]);
+	format_free(ft);
+
 	cdata = xmalloc(sizeof *cdata);
-	cdata->cmd = xstrdup(args->argv[0]);
+	cdata->cmd = shellcmd;
 	cdata->wp_id = wp->id;
 
 	cdata->ctx = ctx;
diff --git a/tmux.1 b/tmux.1
index 33929eff..d708aace 100644
--- a/tmux.1
+++ b/tmux.1
@@ -2704,6 +2704,13 @@ Set clock colour.
 .Xc
 Set clock hour format.
 .Pp
+.It Ic command-prefix Ar string
+String prefixed to commands (apart from a plain shell as set by the
+.Ic default-shell
+option).
+The default is
+.Ql "exec\ " .
+.Pp
 .It Ic force-height Ar height
 .It Ic force-width Ar width
 Prevent
@@ -3016,6 +3023,7 @@ The following variables are available, where appropriate:
 .It Li "mouse_standard_flag" Ta "Pane mouse standard flag"
 .It Li "mouse_utf8_flag" Ta "Pane mouse UTF-8 flag"
 .It Li "pane_active" Ta "1 if active pane"
+.It Li "pane_current_command" Ta "Current command if available"
 .It Li "pane_current_path" Ta "Current path if available"
 .It Li "pane_dead" Ta "1 if pane is dead"
 .It Li "pane_height" Ta "Height of pane"
@@ -3025,6 +3033,7 @@ The following variables are available, where appropriate:
 .It Li "pane_pid" Ta "PID of first process in pane"
 .It Li "pane_start_command" Ta "Command pane started with"
 .It Li "pane_start_path" Ta "Path pane started with"
+.It Li "pane_tabs" Ta "Pane tab positions"
 .It Li "pane_title" Ta "Title of pane"
 .It Li "pane_tty" Ta "Pseudo terminal of pane"
 .It Li "pane_width" Ta "Width of pane"
@@ -3455,7 +3464,11 @@ Miscellaneous commands are as follows:
 .Bl -tag -width Ds
 .It Ic clock-mode Op Fl t Ar target-pane
 Display a large clock.
-.It Ic if-shell Ar shell-command command Op Ar command
+.It Xo Ic if-shell
+.Op Fl t Ar target-pane
+.Ar shell-command command
+.Op Ar command
+.Xc
 .D1 (alias: Ic if )
 Execute the first
 .Ar command
@@ -3464,6 +3477,10 @@ if
 returns success or the second
 .Ar command
 otherwise.
+Before being executed, shell-command is expanded using the rules specified in the
+.Sx FORMATS
+section, including those relevant to
+.Ar target-pane .
 .It Ic lock-server
 .D1 (alias: Ic lock )
 Lock each client individually by running the command specified by the
@@ -3477,6 +3494,10 @@ option.
 Execute
 .Ar shell-command
 in the background without creating a window.
+Before being executed, shell-command is expanded using the rules specified in
+the
+.Sx FORMATS
+section.
 After it finishes, any output to stdout is displayed in copy mode (in the pane
 specified by
 .Fl t