Add exec and pipe functions.

* configure: Check for pipe.

* sysif.c (exec_wrap, pipe_wrap): New static functions.
(sysif_init): Register exec and pipe intrinsics.

* txr.1: Documented exec and pipe.

* tl.vim, txr.vim: Regenerated.

1 files changed, 43 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index 0319b491..2672da68 100644
--- a/txr.1
+++ b/txr.1
@@ -24911,6 +24911,31 @@ or
 .codn nil ,
 rather than zero or nonzero. The others return integer values.
 
+.coNP Function @ exec
+.synb
+.mets (exec < file <> [ args ])
+.syne
+.desc
+The exec function replaces the process image with the executable specified
+by string argument
+.metn file .
+The executable is found by searching the system path.
+
+The
+.meta file
+argument becomes the first argument of the executable, argument zero.
+
+If
+.meta args
+is specified, it is a list of strings. These are passed as the additional
+arguments of the executable.
+
+If
+.code exec
+fails, an exception of type
+.code file-error
+is thrown.
+
 .coNP Functions @ getpid and @ getppid
 .synb
   (getpid)
@@ -24989,6 +25014,24 @@ or
 .codn dup2 ,
 when called with one or two arguments, respectively.
 
+.coNP Function @ pipe
+.synb
+  (pipe)
+.syne
+.desc
+The
+.code pipe
+function, if successful, returns a pair of integer file descriptors
+as a cons cell pair. The descriptor in the
+.code car
+field of the pair is the read end of the pipe.
+The
+.code cdr
+holds the write end.
+
+If the function fails, it throws an exception of type
+.codn file-error .
+
 .SS* Unix Itimers
 Itimers ("interval timers") can be used in combination with signal handling to
 execute asynchronous actions. Itimers deliver delayed, one-time signals,