1. Cs288 Intensive Programming in Linux
Instructor: C F Yurkoski
Section web site:
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2. 6-9-15

3. Linux access
ssh to afs5.njit.edu
or use putty, etc.
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4. Quiz 1 results
Not yet available
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5. Quiz1 revu
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6. Question 1
I => ID => IDD => IDDD => DDDD => 1DDD => 12DD => 123D => 1234
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7. Quiz revu cont.
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8. scoping
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9. Quiz revu
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10. PATH variable colon separated list searched in order
can include relative paths like .
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11. Other commands and misc
& ; ! || &&
cut –c -f
sort –n –r
grep –v –I
$RANDOM $$
read fc tr
diff
ls -l
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12. Grep examples grep "^am" /etc/passwd grep "^[abc]" /etc/passwd | more
grep "^[a-c]" /etc/passwd | more
grep "nologin$" /etc/passwd
grep "^a.*nologin$" /etc/passwd
grep "^a.a.*nologin$" /etc/passwd
grep -v "^a.a.*nologin$" /etc/passwd
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13. Cut examples cut -c 10-20 /etc/passwd cut -c -10 /etc/passwd
cut -d ":" -f 5 /etc/passwd
cut -d ":" -f 2,5 /etc/passwd
cut -d ":" -f 3-5 /etc/passwd
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14. problem 1, due this week
Write a Bash script, count.sh, which builds a table of counts for the commands under /bin which start with each letter. For example, if there are 3 commands starting with "a" (alsaumute, arch & awk) while there may be 2 commands starting with "z" (zcat & zsh). The first and last lines your script will print would be:
a 3
...
z 2
Hint: use loop and array to design and implement this script.
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15. Homework 1 revu ls /bin > /tmp/x
letters=(a b c d e f g h i j k l m n o p q r s t u v w x y z)
for i in ${letters[*]} do
x=0
echo -n "$i "
grep "^${i}" /tmp/x | while read file
let x=x+1
echo $x > count
done
cat count
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16. Problem 2
Write a Bash script, reverse.sh, which reverses the contents of a directory passed as a parameter. For example, assuming /my/dir contains cache cron games lib log run tmp, your program "reverse.sh /my/dir" will return "tmp run log lib games cron cache." Hint: use an array and two functions: main() and reverse(). Do not use the built-in command sort -r.
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17. problem 3
Write a Bash script, filter.sh, which prints those files/directories that have the size greater than the average file size of the directory passed as its first argument . Suppose for example that the directory /my/dir has five files/directories with size in parentheses : a (100) b (10) c (100) d (100) e (20), your program "filter.sh /my/dir" will list "a c d" since the size of each of these 3 files is greater than the average file size of 66. Hint: you can use 3 functions to do this: main, average, and filter, where main calls average and filter, and average computes the average file size of a directory and filter filters out those that have less than the average.
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18. problem 4
Write a Bash script, insert-sort.sh, which sorts a list of command line parameters in ascending order. For example, your command will look something like:  $ insert-sort.sh and type enter. Your program will return:
Use only basic commands and array. Do not use any built-in commands that sort array.
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