Description
CS3423 – Systems Programming
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:
1 lkj293 : x :1539:1543: Albert Einstein :/ home / einstein :/ bin/ bash
2 kkr590 : x :1540:1544: Elvis Presley :/ home / presley :/ bin/ bash
3 nwk409 : x :1541:1545: George Washington :/ home / washington :/ bin/ bash
4 yaa265 : x :1542:1546: Bruce Banner :/ home / banner :/ bin/ bash
5 yhn211 : x :1543:1547: George Harrison :/ home / harrison :/ bin/ bash
6 lfa806 : x :1544:1548: Jane Austen :/ home / austen :/ bin/ bash
7 ilo709 : x :1545:1549: Walt Disney :/ home / disney :/ bin/ bash
8 rfd576 : x :1546:1550: Buzz Aldrin :/ home / aldrin :/ bin/ bash
9 lko889 : x :1547:1551: Marie Curie :/ home / curie :/ bin/ bash
10 cfq219 : x :1548:1552: J . R . R . Tolkien :/ home / tolkien :/ bin/ bash
11 ncz856 : x :1549:1553: Christopher Columbus :/ home / columbus :/ bin/ bash
12 pql747 : x :1550:1554: Julius Caesar :/ home / caesar :/ bin/ bash
Output:
1 rfd576 : x :1546:1550: Buzz Aldrin :/ home / aldrin :/ bin/ bash
2 lfa806 : x :1544:1548: Jane Austen :/ home / austen :/ bin/ bash
3 yaa265 : x :1542:1546: Bruce Banner :/ home / banner :/ bin/ bash
4 pql747 : x :1550:1554: Julius Caesar :/ home / caesar :/ bin/ bash
5 ncz856 : x :1549:1553: Christopher Columbus :/ home / columbus :/ bin/ bash
6 lko889 : x :1547:1551: Marie Curie :/ home / curie :/ bin/ bash
7 ilo709 : x :1545:1549: Walt Disney :/ home / disney :/ bin/ bash
8 lkj293 : x :1539:1543: Albert Einstein :/ home / einstein :/ bin/ bash
9 yhn211 : x :1543:1547: George Harrison :/ home / harrison :/ bin/ bash
10 kkr590 : x :1540:1544: Elvis Presley :/ home / presley :/ bin/ bash
11 cfq219 : x :1548:1552: J . R . R . Tolkien :/ home / tolkien :/ bin/ bash
12 nwk409 : x :1541:1545: George Washington :/ home / washington :/ bin/ bash
Assignment 3: awk Page 1 of 4
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.
Assignment 3: awk Page 2 of 4
Input:
1 UID PID PPID C STIME TTY TIME CMD
2 adz110 5344 5334 0 08:47 pts /2 00:00:00 bash
3 dmq292 6908 6854 0 Jun04 pts /1 00:00:00 bash
4 adz110 7227 7150 0 Jul11 pts /9 00:00:00 who
5 erg474 7466 7461 0 08:54 pts /10 00:00:00 ls
6 dmq292 7966 7960 0 Jun04 pts /13 00:00:00 assign1 . sh if of
7 xle135 8983 8636 0 08:59 pts /15 00:00:00 ssh ctf . cs . utsarr . net
8 zeh458 9057 1980 0 08:59 pts /7 00:00:00 vim prog . c
9 rslavin 9150 9139 0 08:59 pts /16 00:00:00 ps – af
10 xle135 8636 8628 0 08:58 pts /15 00:00:00 bash
Output:
1 User : adz110
2 bash
3 who
4 User : dmq292
5 bash
6 assign1 . sh if of
7 User : erg474
8 ls
9 User : xle135
10 bash
11 ssh ctf . cs . utsarr . net
12 User : zeh458
13 vim prog . c
14
15 Earliest Start Time :
16 dmq292 6908 6854 0 Jun04 pts /1 00:00:00 bash
17
18 Latest Start Time :
19 xle135 8983 8636 0 08:59 pts /15 00:00:00 ssh ctf . cs . utsarr . net
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
Assignment 3: awk Page 3 of 4
$ 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:
• assign3A.sh – a bash script with a single line of code (i.e., one command) for part A
• assign3B.sh – a bash script to invoke for part B.
• assign3B.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.
Submission
Turn your assignment in via Blackboard. Your zip file, named abc123.zip with your personal abc123
should contain only your bash and awk files.
Assignment 3: awk Page 4 of 4
