[Bug 1179287] Re: un-nice things in “set -x”

[Thorsten Glaser]

** Changed in: mksh
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1179287

Title:
  un-nice things in “set -x”

Status in The MirBSD Korn Shell:
  Fix Released
Status in PLD Linux Distribution:
  Confirmed

Bug description:
  One:

  tg at blau:~ $ mksh-R41c -xc $'cat <<"EOF"\nfoo\nEOF\n'                                                            
  + cat
  + <<"EOF"
  foo
  tg at blau:~ $ mksh -xc $'cat <<"EOF"\nfoo\nEOF\n'                                                                 
  + <<"EOF"cat
  foo

  Problem: no whitespace after here document marker.

  
  Two:

  tg at blau:~ $ mksh -xc 'foo=$(bash --version 2>&1 | head -1); echo "=$foo="'
  + + head -1
  + foo='+ + 2>&1 bash --version' 
  + echo '=+ + 2>&1 bash --version='
  =+ + 2>&1 bash --version=
  tg at blau:~ $ mksh-R41c -xc 'foo=$(bash --version 2>&1 | head -1); echo "=$foo="'                                 
  + bash --version
  + head -1
  + 2>&1 
  + foo=GNU bash, version 2.05b.0(1)-release (i386-ecce-mirbsd10)
  + echo =GNU bash, version 2.05b.0(1)-release (i386-ecce-mirbsd10)=
  =GNU bash, version 2.05b.0(1)-release (i386-ecce-mirbsd10)=
  tg at blau:~ $ mksh -xc 'foo=$(bash --version 2>&1 | head -1); echo "=$foo="'                                      
  + + head -1
  + foo='+ + 2>&1 bash --version' 
  + echo '=+ + 2>&1 bash --version='
  =+ + 2>&1 bash --version=

  Questionable: redirection in effect while printing trace.
  Maybe not so nice: PS4 shown twice (what happens with subsequent things?)

  
  Given: stderr redirections/parsing never safe while “set -x” is in effect.
  But maybe we can do better? Something like a trace fd?

  tg at blau:~ $ mksh-R41c -xc 'foo=$((echo foo; bash --version) 2>&1 | head -1); echo "=$foo="'
  + 2>&1 
  + head -1
  + foo=+ echo foo
  + echo =+ echo foo=
  =+ echo foo=
  tg at blau:~ $ mksh -xc 'foo=$((echo foo; bash --version) 2>&1 | head -1); echo "=$foo="'                          
  + + head -1
  + foo='+ 2>&1 + echo foo' 
  + echo '=+ 2>&1 + echo foo='
  =+ 2>&1 + echo foo=

  This clearly shows that having the redirection in effect is not a new thing,
  it just affects more cases now. (The “+ 2>&1 +” is also a cosmetic.)

  Maybe some sort of buffering or pre-preparing the output? Have to look
  at this again.

  
  Thanks to arekm from PLD Linux for reporting these issues.

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