Description

: awk

 

Part A

For this part of the assignment, you will create a single command which will take the contents of a passwd file (usually found in _/etc/passwd) and print it in sorted order by the user’s last name (that is, their surname, not their username). Normally, you could solve this with the following options on sort: $ sort -t: -k6 /path/to/passwd

You, however, must solve this problem with the utilities covered in class so far. You may (and should) use _sort, but you may not use any of its options (e.g., -k, -t, etc).

Example

Input:

• lkj293:x:1539:1543:Albert Einstein:/home/einstein:/bin/bash
• kkr590:x:1540:1544:Elvis Presley:/home/presley:/bin/bash
• nwk409:x:1541:1545:George Washington:/home/washington:/bin/bash
• yaa265:x:1542:1546:Bruce Banner:/home/banner:/bin/bash
• yhn211:x:1543:1547:George Harrison:/home/harrison:/bin/bash
• lfa806:x:1544:1548:Jane Austen:/home/austen:/bin/bash
• ilo709:x:1545:1549:Walt Disney:/home/disney:/bin/bash
• rfd576:x:1546:1550:Buzz Aldrin:/home/aldrin:/bin/bash
• lko889:x:1547:1551:Marie Curie:/home/curie:/bin/bash
• cfq219:x:1548:1552:J.R.R. Tolkien:/home/tolkien:/bin/bash
• ncz856:x:1549:1553:Christopher Columbus:/home/columbus:/bin/bash
• pql747:x:1550:1554:Julius Caesar:/home/caesar:/bin/bash

Output:

• rfd576:x:1546:1550:Buzz Aldrin:/home/aldrin:/bin/bash
• lfa806:x:1544:1548:Jane Austen:/home/austen:/bin/bash
• yaa265:x:1542:1546:Bruce Banner:/home/banner:/bin/bash
• pql747:x:1550:1554:Julius Caesar:/home/caesar:/bin/bash
• ncz856:x:1549:1553:Christopher Columbus:/home/columbus:/bin/bash
• lko889:x:1547:1551:Marie Curie:/home/curie:/bin/bash
• ilo709:x:1545:1549:Walt Disney:/home/disney:/bin/bash
• lkj293:x:1539:1543:Albert Einstein:/home/einstein:/bin/bash
• yhn211:x:1543:1547:George Harrison:/home/harrison:/bin/bash
• kkr590:x:1540:1544:Elvis Presley:/home/presley:/bin/bash
• cfq219:x:1548:1552:J.R.R. Tolkien:/home/tolkien:/bin/bash
• nwk409:x:1541:1545:George Washington:/home/washington:/bin/bash

Script Execution (Part A)

Since the fox machines do not have useful _/etc/passwd files (no first and last names), you will use the one provided with this assignment. Your submission will include a bash file (_assign3A.sh) with exactly one line in it (you do not need a shebang) and should take the path to the passwd file as the first argument. Do not include an awk file or any other files besides _assign3A.sh.

$ assign3A.sh /path/to/passwd

Part B

For this part of the assignment, you will only use the utilities covered in class so far (primarily awk) to create a program for printing user process information. Do not use Python or any programs/utilities not covered in class.

Your program should take the output from _{ps -ef} and print the following for each user having a username matching the abc123 format:

• Username
• List of commands

After listing statistics for each user, the program should print the following information for all users having a username matching the abc123 format:

• Line with earliest start time
• Line with latest start time

Do not use sed, Python, or any other languages/utilities not covered in class.

Example

The example below is an excerpt from the _{ps -ef} command which your program should be able to take as input. Note that if a process began execution on a previous calendar day, its _STIME value will not be in the usual “hours and minutes” format, but rather in “month and day” format. This should be accounted for properly, and thus a simple text/numerical comparison will not suffice.

Input:

UID	PID PPID C STIME TTY	TIME CMD
adz110	5344 5334 0 08:47 pts/2	00:00:00	bash
dmq292	6908 6854 0 Jun04 pts/1	00:00:00	bash
adz110	7227 7150 0 Jul11 pts/9	00:00:00	who
erg474	7466 7461 0 08:54 pts/10	00:00:00	ls
dmq292	7966 7960 0 Jun04 pts/13	00:00:00	assign1.sh if of
xle135	8983 8636 0 08:59 pts/15	00:00:00	ssh ctf.cs.utsarr.net
zeh458	9057 1980 0 08:59 pts/7	00:00:00	vim prog.c
rslavin	9150 9139 0 08:59 pts/16	00:00:00 ps -af
xle135	8636 8628 0 08:58 pts/15	00:00:00 bash

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Output:

User: adz110 bash who User: dmq292 bash assign1.sh if of User: erg474 ls User: xle135 bash ssh ctf.cs.utsarr.net User: zeh458 vim prog.c Earliest Start Time : dmq292                             6908 6854 0 Jun04 pts/1	00:00:00 bash
Latest Start Time : xle135                                 8983 8636 0 08:59 pts/15	00:00:00 ssh ctf.cs.utsarr.net

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Also, if there is a tie for earliest or latest start times, take the one with the UID that comes first alphabetically.

Hint: Consider using _sort to help with grouping.

Script Execution (Part B)

Your program should each be invoked through a single bash file (see below) with input taken from stdin. The resulting output should be printed directly to stdout.

$ assign3B.sh < ps.in

or

$ ps -ef | assign3B.sh

Assignment Data

Sample input files can be found in:

/usr/local/courses/ssilvestro/cs3423/Fall19/assign3.

Script Files

Your submission should consist of multiple files:

• _sh – a bash script with a single line of code (i.e., one command) for part A
• _sh – a bash script to invoke for part B.
• awk – the awk program used in assign3B.awk

Verifying Your Programs

Part A can be tested with the sample input provided with _passwd.in.

Part B can be tested with the sample input provided with _ps.in. Your program should also work with arbitrary input from the _{ps -ef} command.