Bash -x tracing without the clutter

trace_header.sh

#!/bin/bash

# the following sets up a bash script to write the -x tracing to a log file
# in /tmp, with a meaningful, unique name, and a trap to remove it if the
# script completes successfully.  Therefore, if the script fails, in any
# way, the log is there to peruse.  If it succeeds (exit 0) then nothing
# is left behind

# Set up a function to remove the trace file on successful run (exit 0)
cleanup_trace_file() {
  if [[ "$?" == 0 ]]
  then
    /bin/rm $BASH_TRACE_FILE
  else
    printf "$0 died.  Trace file: $BASH_TRACE_FILE\n"
  fi
}

# Set up a tracing prompt that gives date and time info
# e.g., ++10:01:51.536573097    sort -u
# Using PS4 means that this will Not affect the tracing of child processes
PS4='+\t.$(date +%N)  '

# Set up trace output redirection
BASH_TRACE_FILE="/tmp/$(basename $0)-$LOGNAME.trace.$(date +%F_%T).$$"
exec {BASH_XTRACEFD}>$BASH_TRACE_FILE
set -x -e -o pipefail
trap cleanup_trace_file 0

# What follows is a simple test to show that it works
echo stdout
echo stderr 1>&2
Y=0
exit 1