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Tech Tips

From kemiko

Revision as of 21:03, 25 August 2017 by Kemiko (talk | contribs)

Trouble Shooting:

  • Start with the basics...like power, network, etc.

General:

  • Know the animal before trying to tame.
  • Some vendors use MB/GB (decimal...in goups of 1000) and some use MiB/GiB (binary...in groups of 1024).
  • Always query before running modification command(s) whether using the OS, database or apps.
  • Backup or already have a backup before modifying files, database, apps.
  • Learn your editor(s) well...it's functions can save a ton of time
  • Learn all available debugging tool...it can save a ton of time
  • Always use logging
    • Check logs often or write smart alerts that scan logs
    • Rotate logs to keep them manageable
    • tail -f error logs when developing
    • Good paring words: staring/finished, source/target, etc.

Development:

  • Naming
    • Avoid spaces.
    • Use camelCase.
    • Name common items with the common word starting each item.
    • Name same item, but numbered with enough padding to sort correctly. ex: if going to at least 10 use 01-10 instead of 1-10.
    • Name date by number not name and most general to specific. So they sort correctly. ex: 20161231 instead of Dec31-2016, etc.
    • Name using noun first then verb. ex: logCreate, logList, dateStart, dateEnd, etc.
  • Coding
    • Top-down vs bottom-up design
    • Always add comments...you may not remember what you did days, months, years from now
    • Line block brackets up vertically
    • Happy balance between elegance/complexity and readability/maintainability
    • Happy balance between too long and too short variable naming
    • Pick a style and stay consistent...this sometime means following someone else's style when modifying existing code
    • Learn your debugging tool(s)...they can save a ton of time
    • Give some thought to designing your log files...
      • Put the date and time in each record
      • Format well...XML, JSON, delimited, etc.
      • Make sure enough data is included to be helpful

*nix:

  • Type "env" in the shell to display all the environment variables
  • Use "set -x" to debug shell scripts ("set +x" turns it off)
  • Use "set -o vi" to use vi to navigate/modify shell commands ("set +o" turns it off)
  • crontab
    • Put number in 09 format to make easier to read, parse and sort (multiple spaces are fine)
    • Always redirect command output somewhere, log file, /dev/null, etc., so it does not fill up your email


SQL:

  • Always use a where clause even if for everything...where 1 or where 1 = 1. This reminds someone editing the code that this query is operating on EVERYTHING.
  • Comments are handy even in SQL for debugging and as comments. "--comments" is universal, but also /* comments */ in MySQL, {comments} in Informix, etc.
  • Always comment out a drop statement right after executing so it is not accidentally run again
  • Indexes are very important to the performance of a database