Add example to pick.1 for handling empty result set in the shell

This commit bases on a patch provided by Vasily Kolobkov
<polezaivsani@openmailbox.org>. Actually, he also brought the
topic up on the mailing list. Thanks!

Also adjust the man page from nmh's special sequence name `all'
to mmh's name `a' for it.

diff --git a/man/pick.man1 b/man/pick.man1
index 076f99d..2390984 100644 (file)
--- a/man/pick.man1
+++ b/man/pick.man1
@@ -223,7 +223,7 @@ switches are provided, which act just like opening and closing
 parentheses in logical expressions.
 .PP
 If no search criteria are given, all the messages specified on the
-command line are selected (this defaults to `all').
+command line are selected (this defaults to `a').
 .PP
 Once the search has been performed, if the
 .B \-list
@@ -315,7 +315,7 @@ mark(1)
 .SH DEFAULTS
 .nf
 .RB ` +folder "' defaults to the current folder"
-.RB ` msgs "' defaults to all"
+.RB ` msgs "' defaults to all messages"
 .RB ` "\-datefield date" '
 .RB ` \-zero '
 .RB ` \-list "' is the default if no `\-sequence', `\-nolist' otherwise"
@@ -417,5 +417,16 @@ was given, and if its standard output is not a tty, then
 outputs the illegal message number `0'
 when it fails.  This lets the outer command fail gracefully as well.
 .PP
+To account for this case when combining
+.B pick
+with regular shell tools, filter out the message number `0'.
+For example, do
+.PP
+.RS 5
+pick\0...\0|\0fgrep\0-vx\0\&0\0|\0wc\0-l
+.RE
+.PP
+to count the number of messages picked.
+.PP
 The pattern syntax `[l-r]' is not supported; each letter to be
 matched must be included within the square brackets.