From 23d68474116e14757db50f17d040cab5ab0027f6 Mon Sep 17 00:00:00 2001
From: Steffen Nurpmeso <steffen@sdaoden.eu>
Date: Wed, 24 Oct 2018 18:20:33 +0200
Subject: [PATCH] =?utf8?q?Tweak=20[34b66785]=20+=20document=20$COLUMNS=20a?=
 =?utf8?q?nd=20$LINES=20in=20batch=20mode=20(J=C3=B6rg=20Schilling)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

---
 main.c | 12 ++++++++----
 nail.1 | 38 ++++++++++++++++++++++++--------------
 2 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/main.c b/main.c
index a069fb08..f00ade53 100644
--- a/main.c
+++ b/main.c
@@ -477,6 +477,7 @@ a_main_setup_vars(void){
 #endif
       }
    }else
+      /* $COLUMNS and $LINES defaults as documented in the manual */
       n_scrnheight = n_realscreenheight = 24, n_scrnwidth = 80;
    NYD2_LEAVE;
 }
@@ -490,6 +491,7 @@ a_main_setscreensize(int is_sighdl){/* TODO globl policy; int wraps; minvals! */
    struct ttysize ts;
 #endif
    NYD2_ENTER;
+   assert((n_psonce & n_PSO_INTERACTIVE) || (n_poption & n_PO_BATCH_FLAG));
 
    n_scrnheight = n_realscreenheight = n_scrnwidth = 0;
 
@@ -498,19 +500,21 @@ a_main_setscreensize(int is_sighdl){/* TODO globl policy; int wraps; minvals! */
     * only honour it upon first run; abuse *is_sighdl* as an indicator */
    if(!is_sighdl){
       char const *cp;
+      bool_t hadl, hadc;
 
-      if((cp = ok_vlook(LINES)) != NULL){
+      if((hadl = ((cp = ok_vlook(LINES)) != NULL))){
          n_idec_ui32_cp(&n_scrnheight, cp, 0, NULL);
          n_realscreenheight = n_scrnheight;
       }
-      if((cp = ok_vlook(COLUMNS)) != NULL)
+      if((hadc = ((cp = ok_vlook(COLUMNS)) != NULL)))
          n_idec_ui32_cp(&n_scrnwidth, cp, 0, NULL);
 
       if(n_scrnwidth != 0 && n_scrnheight != 0)
          goto jleave;
 
-      /* For batch mode without explicit request, stop now */
-      if(!(n_psonce & n_PSO_INTERACTIVE)){
+      /* In non-interactive mode, stop now, except for the documented case that
+       * both are set but not both have been usable */
+      if(!(n_psonce & n_PSO_INTERACTIVE) && (!hadl || !hadc)){
          n_scrnheight = n_realscreenheight = 24;
          n_scrnwidth = 80;
          goto jleave;
diff --git a/nail.1 b/nail.1
index c63dfc37..a43e589a 100644
--- a/nail.1
+++ b/nail.1
@@ -770,6 +770,11 @@ and
 .Va inbox
 (the latter three to
 .Pa /dev/null ) .
+Also, the values of
+.Ev COLUMNS
+and
+.Ev LINES
+are looked up, and acted upon.
 The following prepares an email message in a batched dry run:
 .Bd -literal -offset indent
 $ LC_ALL=C printf 'm bob\en~s ubject\enText\en~.\enx\en' |\e
@@ -12691,15 +12696,23 @@ $ COLUMNS=80 \*(uA -R
 .Bl -tag -width ".It Ev BaNg"
 .Mx
 .It Ev COLUMNS
-The user's preferred width in column positions for the terminal screen
-or window.
-Queried and used once on program startup, actively managed for child
-processes and the MLE (see
+The user's preferred width in column positions for the terminal screen.
+Queried and used once on program startup in interactive or batch
+.Pf ( Fl \&# )
+mode, actively managed for child processes and the MLE (see
 .Sx "On terminal control and line editor" )
 in interactive mode thereafter.
-Ignored in non-interactive mode, which always uses 80 columns, unless in
-.Fl \&#
-batch mode.
+Non-interactive mode always uses, and the fallback default is 80 columns.
+If in batch mode
+.Ev \&\&COLUMNS
+and
+.Ev LINES
+are both set but not both are usable (empty, not a number, or 0) at
+program startup, then the real terminal screen size will be (tried to
+be) determined once.
+(Normally the
+.Xr sh 1
+manages these variables, and unsets them for pipe specifications etc.)
 .
 .Mx
 .It Ev DEAD
@@ -12756,13 +12769,10 @@ which includes updating
 .
 .Mx
 .It Ev LINES
-The user's preferred number of lines on a page or the vertical screen
-or window size in lines.
-Queried and used once on program startup, actively managed for child
-processes in interactive mode thereafter.
-Ignored in non-interactive mode, which always uses 24 lines, unless in
-.fl #
-batch mode.
+The user's preferred number of lines for the terminal screen.
+The behaviour is as described for
+.Ev COLUMNS ,
+yet the non-interactive and fallback default is 24 (lines).
 .
 .Mx
 .It Ev LISTER
-- 
2.11.4.GIT