Stop subprocesses from using inherited or default PAGER

At startup, set PAGER to "cat" so that any inherited or
default value of PAGER does not affect subprocesses of
Emacs.  Pagers generally won't work when a subprocess
runs under Emacs.
Users can use 'comint-pager' (or other customizations)
to tell subprocesses to use a different specific pager.
* lisp/startup.el (normal-top-level): Set PAGER to 'cat',
if 'cat' is available.  (Bug#72426)

(cherry picked from commit 7811a7d38bb7cb303dc66efa02eb95e75a03f39d)

diff --git a/lisp/startup.el b/lisp/startup.el
index f18795ae6ac29aa9000b1d89ae4908d50148b7b6..738eec772ec95545409c026b5d25557d4e49d355 100644 (file)
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -854,6 +854,12 @@ It is the default value of the variable `top-level'."
     ;; We are careful to do it late (after term-setup-hook), although the
     ;; new multi-tty code does not use $TERM any more there anyway.
     (setenv "TERM" "dumb")
+    ;; Similarly, a subprocess should not try to invoke a pager, as most
+    ;; pagers will fail in a dumb terminal.  Many programs default to
+    ;; using "less" when PAGER is unset, so set PAGER to "cat"; using cat
+    ;; as a pager is equivalent to not using a pager at all.
+    (when (executable-find "cat")
+      (setenv "PAGER" "cat"))
     ;; Remove DISPLAY from the process-environment as well.  This allows
     ;; `callproc.c' to give it a useful adaptive default which is either
     ;; the value of the `display' frame-parameter or the DISPLAY value