Latest revision as of 10:59, 15 October 2017

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...its functionality 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 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.

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" 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

SQL:

• 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