minix question

winstonblue · 05-18-2007, 07:48 PM

Hi all

Could anybody explain the basic functions of the below bash script and what exactly is doing?
Thank you.

#!/bin/sh
# uP2P.sh 0.0.1, 436 characters (excluding comments)
[ $3 ]&&export W=$1 H="$2 $3" K=`mktemp`;Z=/dev/null;e(){ echo "$*";};n(){
nc $* 2>$Z;};x(){ nc -lp ${H#* } -e $1 &>$Z <$Z&};f(){ cat $K|while read h;do
e $W $1 "$2"|n $h;done };case $# in 4)e $W s "$4"|n $H|while read h p f; do
e $W g "$f"|n $h $p>"$f";done;;5)e $H>$K;e $W d $H|n $4 $5>>$K;x $0;;0)x $0
read w c r;[ $W = $w ]&&case $c in s)f l "$r";;g)cat "$r";;a)e $r>>$K;;d)cat $K
f a "$r";;l)ls|grep "$r"|sed "s/^/$H /";;esac;;esac

Matir · 05-18-2007, 10:48 PM

Have you seen this page: http://www.crossflux.org/uP2P/ ?

winstonblue · 05-19-2007, 07:48 PM

.......................

frob23 · 05-19-2007, 08:12 PM

I am not 100% sure that these will work correctly on minix. But it's worth a shot. Simplicity at it's finest.

1)
find ./ -type f -name "*[kl]" -print

2)
who | awk '{print $1}' | sort | uniq

Edit: *nix does not have "folders" it has directories.

winstonblue · 05-19-2007, 08:55 PM

thank you very much
i want to end at k or l before dot. i dont want to examine the extension

i've tried this

find . -name '*[a-zA-Z0-9][kl]' -print

if there is lol.k it wont be a problem
but if there is lol.apk it will print this and i dont want it.
Any ideas?
also i want my results in controlled way. i want every 5 results to press enter to print the next 5 ect.
Thanks for 2) man.

frob23 · 05-20-2007, 01:22 AM

That gets a little bit more complicated (OK, a lot more complicated)... and there is an answer... but before I give this to you, I need to know this isn't homework.

The question just seems too contrived for me to assume it is something you need to so. Explain to me what you are doing, that you need to do this.

Tinkster · 05-20-2007, 01:41 AM

Quote:

Originally Posted by frob23

2)
who | awk '{print $1}' | sort | uniq

Not lazy enough ;}

Code:

who | awk '{print $1}' | sort -u

Cheers,
Tink

frob23 · 05-20-2007, 02:02 AM

lol... you want to see code doing more work than it should? Here is my "solution" to his revised #1:

Code:

find ./ -type f -print | awk 'BEGIN{FS="."}{count=2;while($count){++count};count-=2};$count~/[kl]$/{print $0}' | more

I am putting it up because I am going to bed. It may be because it is 3am but I just couldn't get a regular expression which would match:
took.foo && fanny.pack.mp3

But not:
hello.pak || hill.of.beans

As a bit of explanation (for winstonblue)... because, if this is homework, he's going to understand the answer:

Uhm... forget it... it is too late for me to type it out. For explanation: man awk

Edit: and it pages at the defined page size... not 5 lines... if that is really required he can write his own readline loop in the shell to accomplish it.

Edit 2: This also works (in bash, sh, and probably ksh)

Code:

find ./ -type f -print | while read LINE; do if [ x`echo ${LINE%.*} | grep "[kl]$"` != "x" ]; then echo $LINE; fi; done

I do not know that it is much easier to understand... but it abuses the shell instead of my favorite whipping boy (awK).

winstonblue · 05-20-2007, 09:27 AM

it makes the right results but what is this exactrly doing to work it out?

find ./ -type f -print | while read LINE; do if [ x`echo ${LINE%.*} | grep "[kl]$"` != "x" ]; then echo $LINE; fi; done

frob23 · 05-20-2007, 12:31 PM

Code:

     1  find ./ -type f -print | while read LINE;
     2  do
     3          if [ x`echo ${LINE%.*} | grep "[kl]$"` != "x" ]; then
     4                  echo $LINE;
     5          fi;
     6  done

To help me explain it, I have broken it up into multiple lines and numbered them. This is actually a very small bourne shell script. I gave it as one line to avoid even more confusion. I am going to use the numbers to help explain things. They are not part of the real thing and they are a little arbitrary... I could have numbered them differently if I had laid them out differently.

Line 1: find ./ -type f -print | while read LINE
This bit of code finds all the regular files under the current directory. It then pipes them (|) to a while loop... which stores each line in a variable called LINE. This essentially feeds the actual work part of the program.

Line 2: do
This is the start of our loop. We are going to do all the following steps to each line produced by find above.

Line 3a: `echo ${LINE%.*} | grep "[kl]$"`
The code ${LINE%.*} finds and removes the shortest suffix it can, matching the pattern ".*" which removes any extension. This is where the magic actually happens. The result of the first bit is fed into a grep to see if the end of the line ($) is a k or an l ([kl]).

Line 3b: if [ x` ... ` != "x" ]; then
The 3a bit leaves a string in the if test, if there was a match. So for example, "if [ xtook != x ]; then" would be the test being evaluated and would be true. If there was no match... it would be an empty string and x would equal x so the body of the if loop would not be executed. "!=" tests to ensure that the strings are not equal.

Line 4: echo $LINE;
If the above if test was true, we print out $LINE... which was the name of the file found by find.

Line 5: fi
This closes out if test.

Line 6: done
This signifies the end of our while loop that started with do above... well really started with the while code itself but structurally was wrapped with do and done.

I hope this helped make a little sense of it.

winstonblue · 05-20-2007, 06:16 PM

wow you are the best. Thanks