* Systems Programming Midterm Topics
1. Linux environment / shell commands
   - Common commands
   - Chmod/permissions
   - Wildcards
   - Input/output redirection
   - Shell parsing steps
   - Shell command resolution variables
     - Shell vs environment and their inheritance
   - Exit statuses
   - Subshells / child shells
   - Arithmetic (operators: expansion vs evaluation)
     - Floating arithmetic in bash: how?
2. Bash Scripting
3. ~find~/~grep~
4. Regular expressions (BRE vs ERE)
5. ~sed~

NOTE: No AWK material will be covered on the exam

* Example Questions
1. Answer =True= or =False= for the following statements:
   - [TRUE] The extended regular expression ~{0,1}~ is equivalent to the ~?~ quantifier?
   - [FALSE] An exit status of ~0~ is used to indicate success.
   - [FALSE] Given the string "abc123" the regex ~/[a-z]{1,3}/~ will produce a match of "a".
   - [FALSE] The following loop will never execute:
     #+begin_src bash
     while [ 0 ]; do let i++; echo $i; done
     #+end_src
   - [TRUE] The following loop will never execute:
     #+begin_src bash
     while (( 0 )); do let i++; echo $i; done
     #+end_src
   - [TRUE] ~sed~ will emit the contents of the pattern space, including a trailing newline character, by default at the end of each input cycle.
   - [FALSE] The following bash filename pattern will match all text files in the user's current directory:
     #+begin_src bash
     ls -la .*\.txt
     #+end_src
   - [TRUE] The ~source~ built-in executes the contents of a specified file within the current script (i.e. no subshell is utilized).
   - [FALSE] ~grep~ uses extended regular expressions by default
2. Enter the octal number corresponding to the following Linux file permissions: ~rwxr-x---~
   Answer: ~0750~
3. Write out the erroneous line numbers from the following script (hint there are six):
   #+begin_src bash
   data="./data"
   org_data=/usr/local/courses/ssilvestro/cs3424/Spring21/assign1/

   if [[ $# -eq 1 ]]; then
       data = $1
   else if [[ $# -eq 2 ]]; then
       data = $1
       orig_data = $2
   fi

   if [[! -d $data]]; then
       echo "ERROR: data directory '$data' does not exist"
       exit 1
   fi
   if [[ not -d $orig_data ]]; then
       echo "ERROR: original data directory '$data' does not exist"
       exit 1
   fi
   echo "rm -rf \"$data\"..."
   rm -rf "$data"

   echo "cp -r \"$org_data\" \"$data\"..."
   cp -r "$orig_data" "$data"
   #+end_src
   Answer: ~4,5,6,7,9,13~