Chapter 13: Shell Programming

Boiled down:

Writing a shell script

• .bash_profile to set PATH
  add . to PATH
• Source .bash_profile to run profile
• put Unix commands into file to create a script
• Start with #!/bin/sh
• chmod u+x file to make script executable
• ./script to run file

Parameters and Variables

• myvar=abc
• to access user defined variables - $myvar
• Keyword Variables - $HOME, $PATH
• * is used as wildcard. If a directory listing included two files that start with m (m1 and m2), then ls m* would display m1 and m2
• readonly myvar
  cannot give myvar a value

  Variable attributes can be assigned with the declare statement

  declare -r myvar="I am a constant"

  -a declares as an array

  -f declares as function name

  -r makes variable read only

  myvar=`whoami`

All work herein is subject to copyright. Original content to Dr. Deborah Whitfield, text content (Your UNIX/Linux) to Prentice Hall publishing.