I've created a small diff against tonight's bash master branch for
displaying a (single!) prompt after reading a command but before executing
said command.
It's kind of like trapping debug, but it doesn't output the prompt once for
each subcommand in a pipeline - it's just once for the thing you typed.
Even the following echo's just once:
dstromberg@server:~/src/bash/src$ ./bash
dstromberg@server:~/src/bash/src$ export PS0='fred>
> '
dstromberg@server:~/src/bash/src$ pwd
fred>
/home/dstromberg/src/bash/src
dstromberg@server:~/src/bash/src$ echo 1; echo 2; echo 3
fred>
1
2
3
dstromberg@server:~/src/bash/src$
My hope is that it can be merged into bash master. I didn't see a way of
doing a pull request with savannah, and gmail was refusing to do an
attachment, so I've shar'd the patch file and pasted it below..
Thanks for the cool software!
#!/bin/sh
# This is a shell archive (produced by GNU sharutils 4.11.1).
# To extract the files from this archive, save it to some FILE, remove
# everything before the `#!/bin/sh' line above, then type `sh FILE'.
#
lock_dir=_sh22239
# Made on 2015-10-24 18:51 PDT by .
# Source directory was `/tmp'.
#
# Existing files will *not* be overwritten, unless `-c' is specified.
#
# This shar contains:
# length mode name
# -- -- --
# 2227 -rw-r--r-- ps0-diffs
#
MD5SUM=${MD5SUM-md5sum}
f=`${MD5SUM} --version | egrep '^md5sum .*(core|text)utils'`
test -n "${f}" && md5check=true || md5check=false
${md5check} || \
echo 'Note: not verifying md5sums. Consider installing GNU coreutils.'
if test "X$1" = "X-c"
then keep_file=''
else keep_file=true
fi
echo=echo
save_IFS="${IFS}"
IFS="${IFS}:"
gettext_dir=
locale_dir=
set_echo=false
for dir in $PATH
do
if test -f $dir/gettext \
&& ($dir/gettext --version >/dev/null 2>&1)
then
case `$dir/gettext --version 2>&1 | sed 1q` in
*GNU*) gettext_dir=$dir
set_echo=true
break ;;
esac
fi
done
if ${set_echo}
then
set_echo=false
for dir in $PATH
do
if test -f $dir/shar \
&& ($dir/shar --print-text-domain-dir >/dev/null 2>&1)
then
locale_dir=`$dir/shar --print-text-domain-dir`
set_echo=true
break
fi
done
if ${set_echo}
then
TEXTDOMAINDIR=$locale_dir
export TEXTDOMAINDIR
TEXTDOMAIN=sharutils
export TEXTDOMAIN
echo="$gettext_dir/gettext -s"
fi
fi
IFS="$save_IFS"
if (echo "testing\c"; echo 1,2,3) | grep c >/dev/null
then if (echo -n test; echo 1,2,3) | grep n >/dev/null
then shar_n= shar_c='
'
else shar_n=-n shar_c= ; fi
else shar_n= shar_c='\c' ; fi
f=shar-touch.$$
st1=200112312359.59
st2=123123592001.59
st2tr=123123592001.5 # old SysV 14-char limit
st3=1231235901
if touch -am -t ${st1} ${f} >/dev/null 2>&1 && \
test ! -f ${st1} && test -f ${f}; then
shar_touch='touch -am -t $1$2$3$4$5$6.$7 "$8"'
elif touch -am ${st2} ${f} >/dev/null 2>&1 && \
test ! -f ${st2} && test ! -f ${st2tr} && test -f ${f}; then
shar_touch='touch -am $3$4$5$6$1$2.$7 "$8"'
elif touch -am ${st3} ${f} >/dev/null 2>&1 && \
test ! -f ${st3} && test -f ${f}; then
shar_touch='touch -am $3$4$5$6$2 "$8"'
else
shar_touch=:
echo
${echo} 'WARNING: not restoring timestamps. Consider getting and
installing GNU `touch'\'', distributed in GNU coreutils...'
echo
fi
rm -f ${st1} ${st2} ${st2tr} ${st3} ${f}
#
if test ! -d ${lock_dir} ; then :
else ${echo} "lock directory ${lock_dir} exists"
exit 1
fi
if mkdir ${lock_dir}
then ${echo} "x - created lock directory ${lock_dir}."
else ${echo} "x - failed to create lock directory ${lock_dir}."
exit 1
fi
# = ps0-diffs ==
if test -n "${keep_file}" && test -f 'ps0-diffs'
then
${echo} "x - SKIPPING ps0-diffs (file already exists)"
else
${echo} "x - extracting ps0-diffs (text)"
sed 's/^X//' << 'SHAR_EOF' > 'ps0-diffs' &&
diff --git a/doc/bash.1 b/doc/bash.1
index ec41462..97e46b3 100644
--- a/doc/bash.1
+++ b/doc/bash.1
@@ -2294,6 +2294,13 @@ trailing directory components to retain when
expanding the \fB\ew\fP and
X .B PROMPTING
X below). Characters removed are replaced with an ellipsis.
X .TP
+.B PS0
+The value of this parameter is expanded (see
+.SM
+.B PROMPTING
+below) and presented after a command is read, but before the command is
+executed. The default value is ``'' (the null string).
+.TP
X .B PS1
X The value of this parameter is expanded (see
X .SM
diff --git a/eval.c b/eval.c
index 1f65aac..9f103f0 100644
--- a/eval.c
+++ b/eval.c
@@ -53,6 +53,7 @@ extern int last_command_exit_value, stdin_redir;
X extern int need_here_doc;
X extern int current_command_number, current_command_line_count,
line_number;
X extern int expand_aliases;
+extern char *ps0_prompt;
X
X #if defined (HAVE_POSIX_SIGNALS)
X extern sigset_t top_level_mask;
@@ -157,6 +158,20 @@ reader_loop ()
X
X executing = 1;
X stdin_redir = 0;
+
+ /* After reading a command, before executing it */
+ if (p
