Nobody answered (only need to modify provided below c code)in unix / c languagedesign and implement a simple shell program to read a command with a file redirection. here, use the following file-redirection symbols as follow: "in=infile" for input file named "infile", "out=outfile" for output file named "outfile", "app=appfile" for output to be appended a file named "appfile". for example, "ls out=out. txt" will output the result of the command to a file named out. txt. example commands for shell program1. whoami2. date3. pwd5. ls6. ls out=p1out1.txt7. wc in=p1out1.txt8. cat in=p1out1.txt9. date out=p1out2.txt10. date app=p1out2.txt11. cat in=p1out2.txt12. wc in=p1out1.txt out=p1out4.txt13. cat in=p1out4.txt 15. date