Tech Tips

From kemiko

Trouble Shooting:

  • Start with the power, network, etc.


  • Know the animal before trying to tame.
  • Some vendors use MB/GB ( goups of 1000) and some use MiB/GiB ( 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...its functionality can save a ton of time
  • Learn all available debugging 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 pairing words: staring/finished, source/target, etc.
  • Always learn the background workings. That means learn and use the command line and script NOT just the GUI tools
  • Always check your work! Even when making a simply change...if done wrong can cause large issues.
  • Automate tasks. Automating tasks take a very good understanding of the software and intended goal.


  • 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 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


  • Type "env" and/or "set" in the shell to display all the environment variables
  • Use "set -x" to debug shell scripts ("set +x" turns debugging off)
  • Use "set -o vi" to use vi to navigate/modify shell commands ("set +o" turns vi off)
  • crontab
    • Put number in 09 format to make easier to read, parse and sort (multiple spaces are fine...fields are space delimited)
    • Always redirect command output somewhere, log file, /dev/null, etc.  Otherwise output will be sent to the user's email
    • Command must be one line.  Semicolons are okay to execute mulitple commands
    • The modulus operator can be used to run commands. "*/5" in the minute field will run the command every 5 minutes


  • In general use a where clause even if selecting everything..."where 1" or "where 1 = 1". This reminds someone editing the code that this query is operating on EVERYTHING. Remove the where clause can sometimes greatly optimize code. Make a comment to note there is NO where clause.
  • Comments are handy even in SQL for debugging and understanding. "--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