Operating Systems - 0132410 – הלעפה תוכרעמ 'עשת"א סמסטר ב Spring ...

when the shell is invoked as:myshell1 filename Reuven Mordo Aviv Shalomand it encounters the lineecho Prof. $1 $3in the file, it should executesystem(“echo Prof. Reuven Aviv”) which in turn outputs:Prof. Reuven Avivecho $5should cause an appropriate error message in the standard error4) Perform environment variable substitution on its commands:For instance if the value of the environment variable HOME is/home/cmshalom, and the value of the environment variableTERM is vt100 then:• when the commandcd $HOMEis entered by the user, the current working directory becomes/home/cmshalom.• when the commandpause $TERMis entered by the user, myshell displays vt100 to the standardoutput and wait for the enter to be pressed. 15) Modularization: Separate the program into a set of coherentmodules (i.e. *.c and *.h files)Testing: Test your shell with the sample command file publishedseparately and make sure that you get the correct output (alsopublished).Good Luck !!1 Read about the getenv() function. (man getenv)