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Using GREP

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# 1  
Old 12-05-2010
Power Using GREP
Code:
PING www.l.google.com (209.85.135.99) 56(84) bytes of data.
From 209.85.253.26 icmp_seq=1 Time to live exceeded

--- www.l.google.com ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms
I want to break out of for/while/until loop when the line begins with "64 bytes from [...]".
How do you do that?
PING www.l.google.com (209.85.135.99) 56(84) bytes of data.
64 bytes from mu-in-f99.1e100.net (209.85.135.99): icmp_req=1 ttl=250 time=45.0 ms

--- www.l.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 45.052/45.052/45.052/0.000 ms

Grep always appends NEWLINE after its output. How do you prevent this (anything like echo -n)?
Last edited by courteous; 12-05-2010 at 05:16 PM..
# 2  
Old 12-05-2010
I don't see a for or a while loop in your ping command.
Instead of grep what about this
Code:
# filename is a file with a list of nodes  or ip addresses
while read n
do
  ( ping -c 1 $n | tr -d '\n' )
done < filename > outputfile

Otherwise explain your desired output with an example.
This User Gave Thanks to jim mcnamara For This Post:
courteous
# 3  
Old 12-05-2010
This is the code.
Hi Jim,
above isn't the code but terminal output.

This is the code (user enters target domain | defaults to google.com) which resembles traceroute:
Code:
#!/bin/bash
domain=${1-www.google.com};

for ((i=1; i<=30; i++)) # purely arbitrary (should change to WHILE loop)
do
	if [ "$i" -eq 1 ]; # only to emulate traceroute's first line
	then
		echo -n "mytraceroute to $domain ("
		ping -c 1 -t $i $domain | grep -w 'PING' | grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'
		echo ")" # how do I prevent NEWLINE from GREP? EDIT: Thank you very much Jim!
	fi

	ping -c 1 -t $i $domain | egrep -wv 'PING|64 bytes' | grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'
	echo $? # when GREP finds line that starts as "64 bytes ..." it outputs 1
	#ping -c 1 -t $i $domain # for debugging
done

GREP starts exiting with 1's once I reach the target ... but, the problem is that on the way to the target some servers fail to respond (those stars * * * in traceroute). So I can't rely on
PHP Code:
echo $? 
to tell me when to break out of the loop.

This is the output of the code (look at the trouble-maker "1" in-between):
Code:
mytraceroute to www.google.com (209.85.135.103)
192.168.1.1
0
85.10.0.254
0
95.176.241.10
0
1 # this is way I can't rely on GREP's exit code to break the loop
85.10.0.73
0
[...]
0
72.14.238.128
0
209.85.241.189
0
209.85.253.26
0
1
1
1
^C

Last edited by jim mcnamara; 12-05-2010 at 05:39 PM..
# 4  
Old 12-05-2010
prevent a newline with
Code:
grep command | tr -d '\n'
# so:
grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' | tr -d '\n'

# 5  
Old 12-05-2010
I did that already, I thanked you in the code's comments above. Thank you. Smilie

Below is the before-GREP output. IPs that GREP extracts are in blue.
Code:
PING www.l.google.com (209.85.135.147) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Time to live exceeded
--- www.l.google.com ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

PING www.l.google.com (209.85.135.99) 56(84) bytes of data.
From 95.176.241.10 icmp_seq=1 Time to live exceeded
--- www.l.google.com ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

PING www.l.google.com (209.85.135.106) 56(84) bytes of data.
# This one has "From so-and-so" line missing and makes GREP exit with a 1. Why? EDIT: Because no matches were found, obviously!
--- www.l.google.com ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

PING www.l.google.com (209.85.135.103) 56(84) bytes of data.
From 72.14.219.148 icmp_seq=1 Time to live exceeded
--- www.l.google.com ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

PING www.l.google.com (209.85.135.104) 56(84) bytes of data.
64 bytes from mu-in-f104.1e100.net (209.85.135.104): icmp_req=1 ttl=250 time=41.3 ms 
#finished: from here on GREP exits with 1's

EDIT: To repeat, this output is filtered with this line:
Code:
ping -c 1 -t $i $domain | egrep -wv 'PING|64 bytes' | grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'

Final question: how to make GREP not return exit status 1 on 3rd PING (the one that has this comment: # This one has "From so-and-so" line missing [...])? Smilie
That is, how should I check and break the loop when the first line "64 bytes from [...]" appears (if not using GREP's exit status with echo $?)?
Last edited by courteous; 12-05-2010 at 06:25 PM..
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