Lab 8 Chapter 9

Lab 8 chapter 9 Exercises

Name ________________

1. Explain the following unexpected result:

$ whereis date date: /bin/date … $ echo $PATH .:/usr/local/bin:/usr/bin:/bin $ cat > date echo “This is my own version of date.” $ date Tue Oct 31 10:04:39 MST 2006

2. What are two ways you can execute a shell script when you do not have execute access permission to the file containing the script? Can you execute a shell script if you do not have read access permission?

3. What is the purpose of the PATH variable? a. Set up your PATH variable so that it causes the shell to search the following directories in order: • /usr/local/bin • /usr/bin/Xl1 • /usr/bin • /bin • /usr/kerberos/bin • Your own bin directory (usually bin or .bin in your home directory) • The working directory

b. If a file named doit is in /usr/bin and also in your ~/bin, which one doit will be executed? (Assume that you have execute permission for both of the files.) c. If your PATH variable is not set to search the working directory, how can you execute a program located there? d. Which command can you use to add the directory /user/games to the end of the list of directories in your PATH?

4. Assume that you have made the following assignment: $ person=jenny Give the output of each of the following commands: a. echo $person b. echo ‘$person’ c. echo "$person"

5. The following shell script adds entries to a file named journal-file in your home directory. The script can help you keep track of phone conversations and meetings:

$ cat journal # journal: add journal entries to the file # $HOME/journal-file file=$HOME/journal-file date» $file echo -n "Enter name of person or group: " read name echo "$name" >> $file