Assignment $3$: ThAssignment $5$: Monitoring tools: an introduction to some of the UNIX administrative commands.

In this exercise follow the directions for Assignments $1$ and $3,$ Part $1.$ When a question is asked, put your answers in a file called: admin.docx. For answers consult the man pages and any other Internet sources you can find. Also append to this file the results of doing the following UNIX command$-$line steps on the lxcluster. Bear in mind that different UNIX systems will use variants for administrative come directions are similar to Assignment $1,$ above.

Part $1$:

Step $0$:

$$ Enter the umask $(1)$ command to determine your file creation mask; if not $0022,$ then set the umask to $0022.$

$$ Create a directory $($in a convenient place $$ it will be removed later$)$ called temp

$$ Execute the ls $$l command and note the permissions on the new directory; compare to the file creation mask above

$$ Change directory to temp

$$ Create an empty file $($called newfile.txt$)$ with the shell command: $ $>$newfile.txt

$$ Execute the ls $$l command and note the permissions on the new file; compare to the file creation mask above

Step $1$:

$$ Change directory to the parent $($with $ cd $..)$

$$ Attempt to remove the temp directory; note the failure message

$$ Change directory back to temp

$$ Change the permissions on newfile.txt $($using chmod$)$ to make the file writable by the group

$$ Execute the ls $$l command to confirm

$$ Change the permissions on newfile.txt to make it executable by the owner; execute the ls $$l command to confirm

$$ Execute the newfile.txt $($with the $./$newfile$.$txt command$)$; note that nothing happens $($as it is empty$)$

$$ Delete the newfile.txt file

Step $2$:

$$ Create a shell script file $($called testscript.sh$)$ and add the following commands to it$.($The first line is a comment and instructs the shell to use the bash shell$)$:

#$!/$bin$/$bash

echo listing

ls $$l

echo process status

ps

$$ Make the testscript.sh file executable and readable by the user, the group, and others, but only writable by the owner; execute ls $$l to confirm

$$ Run the script using the $./$testscript$.$sh command

Step $3$:

$$ Create a new file called hardlink.txt with some text in it

$$ hard link this file to a file called newfile.txt file $($using the ln $(1)$ command WITHOUT the $$s; see the man page for ln and get the order right!$)$; confirm with ls $-$l

$$ Confirm that the two files have the same inode number with the ls $$i $*$ command

$$ Remove $($with the rm command$)$ the hardlink.txt file; confirm with the ls $$li command that newfile.txt is still around with the same inode number

$$ Create a file called simlink.txt symbolically linked $($using the ln $$s command$)$ to newfile.txt; confirm using ls $$l $($note that symlink.txt is NOT empty and does NOT have the same number of bytes as the newfile.txt$)$

$$ execute the command: cat symlink.txt to verify that it has the same contents as newfile.txt

$$ Remove the newfile.txt file; confirm with ls $$l

$$ Execute the following command to determine symlink.txt$$s status: file symlink.txt

$$ Remove all files in the temp directory interactively using the rm $$i $*$ command; confirm with ls $-$l

$$ Change directory to the parent directory and remove the temp directory; confirm with ls $$l

Part $2$:

Write a program using the standard library I$/$O functions $($fopen$,$ fread, fwrite, fclose, ferror, feof, and fflush$)$ to read a text file and search it for a string $($specified on the command line$)$ in each line of an input file $($whose name is also specified on the command line$)$; if the string is found substitute another string $($also specified on the command line$)$ ONLY ONCE on the line.

Write the output with the substitutions to the stdout and write any errors to the stderr. The command line should have the form:

assign$03$ infilename string$1$ string$2$

Be sure to check that the argc before proceeding.

So$,$ for the command:

assign$03$ infilename test TESTED

where the infilename file contains:

This is a test file

for assignment $2.$

It is to be tested thoroughly.

It substitutes a string for another uniformly

while reading a file opened

via the standard library.

And this is another test for testing.

Then the output to the stdout should be:

This is a TESTED file

for assignment $3.$

It is to be TESTEDed thoroughly.

It substitutes a string for another uniformly

while reading a file opened

via the standard library.

And this is another TESTED for testing.

$3$ substitutions made

Note that the second occurrence of test $($in the word $$testing$)$ is NOT substituted.

You will want to read the input file one line at a time $($into a buffer$),$ and then search the buffer for the first occurrence of string$1($if any$)$; you may want to make use of strncmp $(3).$ You do not have to open an output file in your program; if you write the substituted text to the stdout you can save its output in a text file with a command like:

$ assign$03$ infilename string$1$ string$2>$ outfilename

In addition, keep a count of the total number of substitutions made and display that number on the stderr at the end of execution.