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HOWTO_Debug

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Simon Fowler edited this page Jun 30, 2017 · 2 revisions
  1. summary How to view debugging output.
  2. labels Phase-QA,Phase-Implementation,Phase-Support,Phase-Deploy

Introduction

The executables included in the Advanced Shell History program are coded to use a variable-visibility-level logging system. This is similar to many popular logging systems such as log4j or google-glog.

In a nutshell, there are five levels of severity, each higher than the previous:

  • DEBUG -  The lowest level.  Used for troubleshooting and not for normal use.
  • INFO - Intended for significant events in the code that don't indicate a problem.
  • WARNING - Intended to indicate a potential problem, but not necessarily something wrong.
  • ERROR - This is an unexpected condition or problem.  Execution will continue, but this warrants user attention.
  • FATAL - The highest level.  Messages logged as fatal will be logged and then execution of the program will be halted.

Users can specify a visibility threshold in the settings - all levels of severity below the threshold are suppressed.

Details

The program defines several configuration settings that allow you to customize where logged output is sent and which levels are to be visible. See this guide to configuration for general configuration details.

The settings you want to be aware of are:

#
# Logging:
#

# ASH_CFG_LOG_FILE - Defines where logged messages are written.
ASH_CFG_LOG_FILE="${HOME}/.ash/ash.log"  # Default: ~/.ash/ash.log

# ASH_CFG_LOG_LEVEL - The minimum severity level that is logged to
#                     ASH_CFG_LOG_FILE.
#                     Severities (in increasing order):
#                       DEBUG, INFO, WARNING, ERROR, FATAL
ASH_CFG_LOG_LEVEL='DEBUG'  # Default: WARNING

# ASH_CFG_LOG_DATE_FMT - The timestamp format string used by the logger.
ASH_CFG_LOG_DATE_FMT='%Y-%m-%d %H:%M:%S %Z: '  # Default: %Y-%m-%d %H:%M:%S %Z:

Tips

If you want to view debugging output on the console, you can set ASH_CFG_LOG_FILE=/dev/stderr in your shell environment. When you are done, you can reset the variable to ASH_CFG_LOG_FILE=~/.ash/ash.log.

If you find a bug, please turn on debugging to level DEBUG and include debug output to support your case when you raise an issue.

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