Reference no: EM132571892

Part A

Objectives : Develop CLI/Shell and vi skills. 

Explore positional arguments and parameter expansion.

Exercise: 1. Login to your server vm using ssh login. Do not use a ttysession!

2. Launch tmux , maximize it and split into two vertical panes. Use LHS to write the script and RHS to execute it. 3. Write a shell script 300123456-a3.sh to perform the following : 3.1. 05pts. Use command substitution to pass the current working directory in $1 . 3.2. 05pts. Exit with return code 2 immediately if the number of arguments passed is zero. 3.3. 05pts. Create an empty file samplefile if it does not exist in current working directory. 3.4. 05pts. Store the absolute path to samplefile in a variable _SFILE using $1 and the filename. 3.5. 05pts. Use parameter expansion to extract the filename samplefile from _SFILE .Hint : Remove all characters as longest matching pattern from the start of the absolute path. 3.6. 05pts. Use parameter expansion to extract the path info in _SFILE by removing the filename from the end. 3.7. 05pts. Print 3.5 and 3.6 in a single echo statement and exit with 0. 3.8. 05pts. Print the contents of your script with line numbers. 4. All your coursework must comply with submission guidelines to be accepted.

Part b

Objectives : 1. Use for and while loops in CLI. 2. Task automation using at and cron commands.

Exercise : 1. Login to your server as regular user using ssh. 2. Launch tmux and split the terminal into two vertical panes. 3. 15pts. Using for loop in CLI : 3.1. In the left pane, process the contents of /etc directory to print filemode, filesize, and filename of text files using a for loop, command substitution, and pipes. a) Use ls -1 /etc when creating the list in the for statement. b) In the body of the loop, use test command to see if the entry is a file or a directory. Proceed only if it's a file, ignore if it's a directory. Note that you will need to prepend /etc to filename because ls -1 returns only the filename as in ls -l /etc/$_FNAME. c) Use tr command to squeeze multiple blanks into one blank in each line, like tr -s' ' . d) Use cut command to select individual fields in an input line. e) Use tr command again to translate field separator, aka delimiter, blank to a tab as in tr ' ' '\t' . f) 0pts. Use head command to limit the size of listing. 4. 15pts. Using while loop in CLI to read from a file : 4.1. In the right pane, read the contents of ls.etc file to print filemode, filesize and filename of text files using a while loop. a) Save the output from ls -l /etc command in a file ls.etc . b) Use a while loop to read ls.etc line by line into a variable _LINE. c) Use echo command to pipe the output to cut command to select the fields to print. d) Replace delimiter blank with tab character. e) Use grep to filter in only the lines that don't have a d in the first position as in grep -v ^d . f) 0pts. Use head command to limit the size of listing. 5. 10pts. Task scheduling using at : 5.1. Create a shell script 300*.at which a) tests if a file /tmp/norun does exist. If yes, it will echo removing /tmp/norun with a timestamp of the form YYYYMMDD-HH:MM:SS to 300*.log (hint: use %Y%m%d-%T format of the date command) and remove /tmp/norun . b) reschedules itself to run 5 minutes later using at command. 5.2. Create a cron entry to run a script 300*.crn every 1 minute every day of every month.