From 90bb66e1f1cee7d63ac0d011e06662920431c718 Mon Sep 17 00:00:00 2001
From: John Ankarstrom <john@ankarstrom.se>
Date: Tue, 6 Jul 2021 22:30:38 +0200
Subject: Execute commands in the same shell process

---
 build.1 | 14 ++++++++++++--
 build.c |  5 ++++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/build.1 b/build.1
index a722d1c..1543177 100644
--- a/build.1
+++ b/build.1
@@ -44,6 +44,16 @@ Build information is encoded in two ways:
 .Pp
 There can be multiple command lines,
 but only one dependency line.
+.Pp
+Unlike
+.Xr make 1 ,
+.Nm
+executes all command lines,
+joined by newlines,
+in the same shell process.
+This means that you can keep state across multiple commands.
+Note that all commands are executed
+regardless of the exit status of previous commands.
 .
 .Sh EXAMPLES
 .Pp
@@ -52,8 +62,8 @@ Assuming that the file
 starts with the following text,
 .Bd -literal -offset indent
 \&.\\" This document is built with the following shell commands:
-\&.\\"   $ refer -p refs doc.t | troff -ms | dpost > doc.ps
-\&.\\"   $ ps2pdf doc.ps > doc.pdf
+\&.\\"   $ refer -p refs doc.t | troff -ms | dpost > doc.ps &&
+\&.\\"   $ ps2pdf doc.ps > doc.pdf &&
 \&.\\"   $ rm doc.ps
 \&.
 \&.\\" It depends on the following files:
diff --git a/build.c b/build.c
index ea17de3..6af16f0 100644
--- a/build.c
+++ b/build.c
@@ -155,10 +155,13 @@ uptodate:
 
 build:
 		/* run commands */
+		buf[0] = 0;
 		for (j = 0; j < icmd; j++) {
 			fprintf(stderr, "%s: %s\n", argv[i], cmd[j]);
-			system(cmd[j]);
+			strncat(buf, cmd[j], sizeof(buf)-1);
+			strncat(buf, "\n", sizeof(buf)-1);
 		}
+		system(buf);
 
 done:
 		fclose(fp);
-- 
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