54783: improve checkptycmd

With the previous (and now fallback) version of checkptycmd(), doing
this:
zpty foo 'while read; do echo hi; done'
zpty (or zpty -t foo)

would hang forever, which seems counterintuitive to the purpose of
listing processes (or testing if a process is running).

1 files changed, 12 insertions, 0 deletions

diff --git a/Test/V08zpty.ztst b/Test/V08zpty.ztst
index 057db2e18..cad6bb9bd 100644
--- a/Test/V08zpty.ztst
+++ b/Test/V08zpty.ztst
@@ -25,3 +25,15 @@
   zpty -d cat
 0:zpty with a process that does not set up the terminal: write via stdin
 >a line of text
+
+  zpty loop 'while read; do echo hello; done'
+  zpty -w loop hi
+  zpty -rt loop | tr -d $'\r'
+  zpty -w loop hi
+  zpty -t loop
+  zpty -rt loop | tr -d $'\r'
+  zpty -rt loop
+  zpty -d loop
+0:zpty doesn't duplicate data
+>hello
+>hello