New command, if-shell (alias if). Executes the tmux command in the second

argument if the shell command in the first succeeds, for example:

       if "[ -e ~/.tmux.conf.alt ]" "source .tmux.conf.alt"

Written by Tiago Cunha, many thanks.

Makefile

@@ -22,7 +22,7 @@ SRCS=	arg.c attributes.c buffer-poll.c buffer.c cfg.c client-fn.c \
 	cmd-send-prefix.c cmd-server-info.c cmd-set-buffer.c cmd-set-option.c \
 	cmd-set-password.c cmd-set-window-option.c cmd-show-buffer.c \
 	cmd-show-options.c cmd-show-window-options.c cmd-source-file.c \
-	cmd-split-window.c cmd-start-server.c cmd-string.c \
+	cmd-split-window.c cmd-start-server.c cmd-string.c cmd-if-shell.c \
 	cmd-suspend-client.c cmd-swap-pane.c cmd-swap-window.c \
 	cmd-switch-client.c cmd-unbind-key.c cmd-unlink-window.c \
 	cmd-up-pane.c cmd.c colour.c grid-view.c grid.c input-keys.c \

cmd-if-shell.c

@@ -0,0 +1,176 @@
+/* $OpenBSD$ */
+
+/*
+ * Copyright (c) 2009 Tiago Cunha <me@tiagocunha.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tmux.h"
+
+/*
+ * Executes a tmux command if a shell command returns true.
+ */
+
+int	cmd_if_shell_parse(struct cmd *, int, char **, char **);
+int	cmd_if_shell_exec(struct cmd *, struct cmd_ctx *);
+void	cmd_if_shell_send(struct cmd *, struct buffer *);
+void	cmd_if_shell_recv(struct cmd *, struct buffer *);
+void	cmd_if_shell_free(struct cmd *);
+void	cmd_if_shell_init(struct cmd *, int);
+size_t	cmd_if_shell_print(struct cmd *, char *, size_t);
+
+struct cmd_if_shell_data {
+	char *cmd;
+	char *sh_cmd;
+};
+
+const struct cmd_entry cmd_if_shell_entry = {
+	"if-shell", "if",
+	"shell-command command",
+	0,
+	cmd_if_shell_init,
+	cmd_if_shell_parse,
+	cmd_if_shell_exec,
+	cmd_if_shell_send,
+	cmd_if_shell_recv,
+	cmd_if_shell_free,
+	cmd_if_shell_print
+};
+
+void
+cmd_if_shell_init(struct cmd *self, unused int arg)
+{
+	struct cmd_if_shell_data	*data;
+
+	self->data = data = xmalloc(sizeof *data);
+	data->cmd = NULL;
+	data->sh_cmd = NULL;
+}
+
+int
+cmd_if_shell_parse(struct cmd *self, int argc, char **argv, char **cause)
+{
+	struct cmd_if_shell_data	*data;
+	int				 opt;
+
+	self->entry->init(self, 0);
+	data = self->data;
+
+	while ((opt = getopt(argc, argv, "")) != -1) {
+		switch (opt) {
+		default:
+			goto usage;
+		}
+	}
+	argc -= optind;
+	argv += optind;
+	if (argc != 2)
+		goto usage;
+
+	data->sh_cmd = xstrdup(argv[0]);
+	data->cmd = xstrdup(argv[1]);
+	return (0);
+
+usage:
+	xasprintf(cause, "usage: %s %s", self->entry->name, self->entry->usage);
+
+	self->entry->free(self);
+	return (-1);
+}
+
+int
+cmd_if_shell_exec(struct cmd *self, struct cmd_ctx *ctx)
+{
+	struct cmd_if_shell_data	*data = self->data;
+	struct cmd_list			*cmdlist;
+	char				*cause;
+	int				 ret;
+
+	if ((ret = system(data->sh_cmd)) < 0) {
+		ctx->error(ctx, "system error: %s", strerror(errno));
+		return (-1);
+	} else if (ret != 0)
+		return (0);
+
+	if (cmd_string_parse(data->cmd, &cmdlist, &cause) != 0) {
+		if (cause != NULL) {
+			ctx->error(ctx, "%s", cause);
+			xfree(cause);
+		}
+		return (-1);
+	}
+
+	if (cmd_list_exec(cmdlist, ctx) < 0) {
+		cmd_list_free(cmdlist);
+		return (-1);
+	}
+
+	cmd_list_free(cmdlist);
+	return (0);
+}
+
+void
+cmd_if_shell_send(struct cmd *self, struct buffer *b)
+{
+	struct cmd_if_shell_data	*data = self->data;
+
+	buffer_write(b, data, sizeof *data);
+	cmd_send_string(b, data->cmd);
+	cmd_send_string(b, data->sh_cmd);
+}
+
+void
+cmd_if_shell_recv(struct cmd *self, struct buffer *b)
+{
+	struct cmd_if_shell_data	*data;
+
+	self->data = data = xmalloc(sizeof *data);
+	buffer_read(b, data, sizeof *data);
+	data->cmd = cmd_recv_string(b);
+	data->sh_cmd = cmd_recv_string(b);
+}
+
+void
+cmd_if_shell_free(struct cmd *self)
+{
+	struct cmd_if_shell_data	*data = self->data;
+
+	if (data->cmd != NULL)
+		xfree(data->cmd);
+	if (data->sh_cmd != NULL)
+		xfree(data->sh_cmd);
+	xfree(data);
+}
+
+size_t
+cmd_if_shell_print(struct cmd *self, char *buf, size_t len)
+{
+	struct cmd_if_shell_data	*data = self->data;
+	size_t				off = 0;
+
+	off += xsnprintf(buf, len, "%s", self->entry->name);
+	if (data == NULL)
+		return (off);
+	if (off < len && data->sh_cmd != NULL)
+		off += cmd_prarg(buf + off, len - off, " ", data->sh_cmd);
+	if (off < len && data->cmd != NULL)
+		off += cmd_prarg(buf + off, len - off, " ", data->cmd);
+	return (off);
+}

cmd.c

@@ -42,6 +42,7 @@ const struct cmd_entry *cmd_table[] = {
 	&cmd_down_pane_entry,
 	&cmd_find_window_entry,
 	&cmd_has_session_entry,
+	&cmd_if_shell_entry,
 	&cmd_kill_pane_entry,
 	&cmd_kill_server_entry,
 	&cmd_kill_session_entry,

tmux.1

@@ -711,6 +711,16 @@ This command only works from inside
 .D1 (alias: Ic has )
 Report an error and exit with 1 if the specified session does not exist.
 If it does exist, exit with 0.
+.It Xo Ic if-shell
+.Ar shell-command
+.Ar command
+.Xc
+.D1 (alias: Ic if )
+Execute
+.Ar command
+if
+.Ar shell-command
+returns success.
 .It Xo Ic kill-pane
 .Op Fl p Ar pane-index
 .Op Fl t Ar target-window

tmux.h

@@ -1101,6 +1101,7 @@ extern const struct cmd_entry cmd_detach_client_entry;
 extern const struct cmd_entry cmd_down_pane_entry;
 extern const struct cmd_entry cmd_find_window_entry;
 extern const struct cmd_entry cmd_has_session_entry;
+extern const struct cmd_entry cmd_if_shell_entry;
 extern const struct cmd_entry cmd_kill_pane_entry;
 extern const struct cmd_entry cmd_kill_server_entry;
 extern const struct cmd_entry cmd_kill_session_entry;