Question

1. What are the names of the parts of a UNIX command? list them, and give a brief description of each.

2. Can multiple UNIX commands be typed on the same single command line? Explain how

3. How can you find out which utilities are available on your system for editing files? Which utilities are available for editing on your system?

4. What does the following command do? What is $PATH and echo $PATH?

5. What is the result of giving the which utility the name of a command that resides in a directory that is nor in your search path?

Answer 1

1. The names of parts of a UNIX command is as follows:
   1. Command name:- This is the name by which the command to be used is identified.
   2. Options/s:- These are single letters preceded by a hyphen. These instruct UNIX to perform an action by executing the command in a particular way which is determined by the option used.
   3. FIlename/s:- There are many commands in UNIX that operate on a file. These commands require the filename of the file to be specified just after the command.
   4. Argument/s:- UNIX commands require some information in order to their job. These pieces of information are known as arguments.
2. Yes, multiple UNIX commands can be typed on the same command line. These are possible in the following ways:
   1. separating commands written on the same line using ';'. For example, ls;pwd.
   2. using operators like '&&' or '||'. For example, cd MyDir && ls. This command makes MyDir as the present working directory and lists out its content.
   3. Using pipes. The syntax for the same is command1 | command2 | command3... | commandN.
3. In order to find out which utilities are available on your system, one can use the command apropos editor. The utilities available for editing on my system are vim, ex, gedit, pico, vi.
4. 1st Part

(Command not given)

2nd part

$PATH: In UNIX, $PATH is an environmental variable. It is used by the shell to know where it should search for the executable files in response to the command entered by the user. In other words, it tells the location of the executable files to the shell.

echo $PATH: This is used to view the directories specified by the PATH variable.

5. If we give the utility, the name of a command residing in a directory that is not in our search path then it will not work. This is because the utility cannot find the destination.