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What's wrong with my sed?

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Top Forums Shell Programming and Scripting What's wrong with my sed?
# 1  
Old 05-02-2012
What's wrong with my sed?
Code:
lyang0@lyang0-OptiPlex-755:~$ cat xx
Settings for eth1:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
	Speed: 1000Mb/s
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: off
	Supports Wake-on: pumbg
	Wake-on: g
	Current message level: 0x00000001 (1)
			       drv
	Link detected: yes

Code:
lyang0@lyang0-OptiPlex-755:~$ cat xx |grep "Speed" |sed 's/.* \([0-9]*\)Mb.*/\1/g'
1000

but I don't want to use the second pipe, so I use below cmd, but I got un-expected ansower, anyone correct me?
Code:
lyang0@lyang0-OptiPlex-755:~$ cat xx |sed '/Speed/s/.* \([0-9]*\)Mb.*/\1/g'
Settings for eth1:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
1000
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: off
	Supports Wake-on: pumbg
	Wake-on: g
	Current message level: 0x00000001 (1)
			       drv
	Link detected: yes

# 2  
Old 05-02-2012
Hi, try:

Code:
sed -n '/Speed/s/.* \([0-9]*\)Mb.*/\1/gp' xx

alternatively:
Code:
awk '/Speed/{print $2+0}' xx

# 3  
Old 05-02-2012
try with awk

Code:
 
$ nawk '/Speed/ {sub("Mb/s","",$2);print $2}' test.txt
1000

# 4  
Old 05-02-2012
Quote:
Originally Posted by Scrutinizer
Hi, try:

Code:
sed -n '/Speed/s/.* \([0-9]*\)Mb.*/\1/gp' xx

alternatively:
Code:
awk '/Speed/{print $2+0}' xx

Greate it works, can you explain the $2+0, I don't understand it, or I google something I don't know
# 5  
Old 05-02-2012
Hi, by adding the number 0 to the string contained in $2, it is forced into numeric context, so "Mb/s" gets dropped and 1000 remains...
This would be an alternative way of doing the same..
Code:
awk '/Speed/{print int($2)}' xx

# 6  
Old 05-02-2012
Quote:
Originally Posted by Scrutinizer
Hi, by adding the number 0 to the string contained in $2, it is forced into numeric context, so "Mb/s" gets dropped and 1000 remains...
This would be an alternative way of doing the same..
Code:
awk '/Speed/{print int($2)}' xx

Thanks for the explain, I never see this usage before in the book, My book is bad
# 7  
Old 05-02-2012
Maybe it is not so much bad, but it chooses to show examples that are perhaps a bit easier to understand. The same could have been achieved with the sub function like itkamaraj showed, which may be the most accessible method. There are just many ways of doing it, it could for example also be done with the field separator
Code:
awk -F': |Mb/s' '/Speed/{print $2}' infile

or
Code:
awk -F'Speed: |Mb/s' 'NF==3{print $2}' infile

or with split
Code:
awk '/Speed/{split($2,T,"Mb/s"); print T[1]}' infile

Last edited by Scrutinizer; 05-02-2012 at 07:37 AM..
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