command line quizzes part 2

Here's part two of the command line quizzes. Part one can be found here.

Q: Given that "top -b -n 1" gives the following output, write a script which kills all processes that use more than 25% of the processing power.

Tasks: 85 total, 1 running, 84 sleeping, 0 stopped, 0 zombie
Cpu(s): 4.7%us, 0.6%sy, 0.0%ni, 93.7%id, 0.8%wa, 0.2%hi, 0.1%si, 0.0%st
Mem: 506372k total, 495416k used, 10956k free, 12364k buffers
Swap: 0k total, 0k used, 0k free, 195588k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6159 root 19 -1 357m 38m 5380 S 2.0 7.9 7:02.21 X
6271 mats 20 0 123m 38m 25m S 2.0 7.8 1:33.09 amarokapp
6287 mats 20 0 25840 9916 7324 S 2.0 2.0 0:29.45 gkrellm
1 root 20 0 1612 544 472 S 0.0 0.1 0:00.84 init
2 root 15 -5 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/0
4 root 15 -5 0 0 0 S 0.0 0.0 0:02.08 ksoftirqd/0
5 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
6 root 15 -5 0 0 0 S 0.0 0.0 0:00.16 events/0
7 root 15 -5 0 0 0 S 0.0 0.0 0:00.00 khelper
42 root 15 -5 0 0 0 S 0.0 0.0 0:00.11 kblockd/0

Here's a solution.

#!/bin/bash
#script to kill all processes which use more than 25% of the cpu
top -b -n 1 | awk 'NR >= 8 && $9 > 25 {print $1}' | xargs -r kill

Thanks to Ralph for this solution.

Q: Given the following two CSS files, write a script to verify that every class is only defined once (catch duplicate declarations).

File 1: first.css

body {font-family:Verdana;}
.header {font-size:90%;  }
.article {line-height:1.1em;}
.footer {font-size:80%;  }
.main .left #contents {float:left;}

File 2: second.css

#article .title {font-size:110%;}
.header {font-weight:bold;}
.email {font-family:Courier;}
.address {line-height:0.8em;}
.left {text-align:left;}

Here's a solution.

#!/bin/bash
#script to find out if two css files contain the same class name

#Use sed to filter out the css rules and put all the ids and classes on their own line
#Use sed again to only keep the class names
#Use sort and uniq to figure out the dups
classnames=$(sed -e 's/\([^{]*\).*/\1/g' -e 's/ /\n/g' $@ | sed -n -e '/\.\w\+/ p' | sort | uniq -dc | sort -r)
echo -e "\nDuplicate   classes:\n"
echo "$classnames"
echo -e "\nGrepped     files:\n"
#grep the files in argument for the class names found above
grep --color -n "$(echo "$classnames" | awk '{print $2}' | sed -e 's/\./\\./g' -e 's/\n/\|/g')" $@

It can be called like so.

./dupcss.sh first.css second.css

And gives the following output.

Duplicate classes:

2 .left
2 .header

Grepped files:

first.css:2:.header {font-size:90%;}
first.css:5:.main .left #contents {float:left;}
second.css:2:.header {font-weight:bold;}
second.css:5:.left {text-align:left;}

Grepping the files and displaying the results is just a convenience to the user.


I don't have any other quizzes on the back burner but I do have a few good links:

• Getting started with awk


• Sed - an intro and tutorial


• bash how-to


• vim cheat sheet


• cheat-sheets.org