Exercises for shell script & perl (chapter10, due on 12/30 before the class)
1.
Write a script to check whether a file exists and is readable. If the number of
argument is not one, then print “Usage: chkfile file” and exit. Otherwise, print
“File exists but is not readable”, “File is readable”, or “File doesn’t exist”
correspondingly.
2.
Write an argument check shell script, called argCheck.sh, so that we can check
the arguments (using $#) to the command. The script expects one or two
arguments. If the number of arguments is incorrect, it displays an error message
3.
and terminates with exit status 1. If we have two arguments, we set the variables
from and to. If we have only one argument, then it becomes the value of to.
Compose a command search script, called cmdSearch.sh, using for and if
constructs. The script locates a command, which is executable, on the command
search path ($PATH) and displays its full pathname. If the command is not found,
4.
it displays a message “$cmd not on $PATH”.
Write a script, called append.sh, to append either the standard input or a file to
the end of the other file. For example, $append.sh file will ask for input line by
line, put in the file until ctrl+d, and $append.sh file1 file2 will appends file1 to
the end of file2.
5.
6.
Write a script, named comc.sh, to automatically select the last C program, link to
three filenames: vic, comc, runc, and then it edits, compiles, and executes the
selected file. That is, vi filename.c, filename (as an executable file), and cc -o
filename filename.c. You need to check if the existence of a C program in the
current directory. Once you have finished the coding, the only thing left is to
create three links: ln comc.sh comc; ln comc.sh runc; and ln comc.sh vic.
(hint: use expr to remove the suffix .c and use case for the choices)
Write a one-liner perl instruction to (i) change the she-bang line to
#!/usr/local/bin/perl in all .pl files in the current directory. (ii) convert all
characters in a file, called foo, to uppercase, and write the changes back to the
same file without using redirection.
7.
8.
Write a perl program to convert a binary number specified as argument to
decimal. (hint: use the reverse function,)
Write a perl program that changes the login shell of users in /etc/passwd. The
shell has to be changed to /bin/bash for all users with UID greater than 100 and
whose current shell is /usr/bin/pdksh or /bin/ksh. The output has to be written
to a separate file, named passwdChanged, in the current directory.
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