Bash Programming

• We need to spend some time writing programs in a few scripting languages.
• I will start with bash. (UG)
• I can write bash scripts with a manual
• But I would much rather go to python for most tasks.
• I am using Bash Shell Scripting
• Variables
  • Everything is a string unless otherwise noted.
  • And the shell will perform variable expansion all over the place.
  • ${varname} is safest, but often skipped.
  • $varname is probably ok, but sometimes a problem
  • "$varname" is good too
  • but ' suppresses the interpretation
  • '$varname' is the litteral string
• There are some special variables.
  • $? - the exit status of the most recently executed command
  • $$ the process id.
  • $0, $#, $@ and $* as we have seen.
• And an entire list of others