Implementing Pipelines (OPERATING SYSTEMS)

Exercise 5 The simple shell that we used in Lab 1 is to be extended so that the user can run command pipelines such as: ls | wc The parser already recognizes | and the function pipecmd has been created for you. The only code you must write is for the '|' case in runcmd. You might find the man pages for pipe, fork, close, and dup useful. Test that you can run the above pipeline. The wc program may be in the directory /usr/bin/ and in that case you can type the absolute pathname /usr/bin/wc to run word-count. The command which wc can help find which directory in the shell's search path has an executable named wc. Make sure you use the right absolute pathnames for the programs. Now you should be able to run the command correctly by using absolute pathnames: $ /usr/bin/ls | /usr/bin/wc -l Note: I have got the code from previous exercise