awk question


 
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# 8  
Old 07-23-2012
Quote:
Originally Posted by Scrutinizer
I get an empty line...
That is strange...what OS and system are you on.
# 9  
Old 07-23-2012
Quote:
Originally Posted by shamrock
That is strange...what OS and system are you on.
I tried it on Ubuntu and OSX...
# 10  
Old 07-23-2012
I dont have Ubuntu but the ex command works on my hpux aix solaris and rhel boxes so frankly im at a loss...Smilie
# 11  
Old 07-23-2012
Both OSX and Ubuntu offer vim instead of vi, so that is probably where the difference comes from. I just tried it on RHEL5.8 (or rather CentOS 5.8) and it does not work there either...
# 12  
Old 07-24-2012
I thought I can get it from
Code:
awk '/5555/{print $(NR-2)}'

but it don't get the results, what's wrong with me
# 13  
Old 07-24-2012
Quote:
Originally Posted by yanglei_fage
I thought I can get it from
Code:
awk '/5555/{print $(NR-2)}'

but it don't get the results, what's wrong with me
That is possible only if you save the lines as they are read in an array and at the end you print out the 2nd last item...
# 14  
Old 07-24-2012
Quote:
Originally Posted by shamrock
Yet another way with ex...
Code:
ex +'/5555/-2 | q!' file

Something to keep in mind when choosing how to pass commands to ex: When ex (and ed) are reading commands from standard input, they abort with a meaningful exit status at the first sign of trouble. However, with ex, when commands are given as an option-argument (ed doesn't support this), if there's an error, ex will prompt for another command and wait. In this case, for example, if there was no line matching /5555/, ex would not quit. Usually (but not always), this is not ideal.

Also, the output of that command depends on local settings. It may or may not print a line number. If the output is to be processed by a script, this adds unnecessary complexity (either settings need to be overridden or something downstream needs to handle both possible formats).

In my opinion, the simplicity of ed would be an asset for this task.



Quote:
Originally Posted by Scrutinizer
I get an empty line...
Quote:
Originally Posted by Scrutinizer
I tried it on Ubuntu and OSX...
Quote:
Originally Posted by shamrock
I dont have Ubuntu but the ex command works on my hpux aix solaris and rhel boxes so frankly im at a loss...Smilie
Quote:
Originally Posted by Scrutinizer
Both OSX and Ubuntu offer vim instead of vi, so that is probably where the difference comes from. I just tried it on RHEL5.8 (or rather CentOS 5.8) and it does not work there either...
Using an old debian where ex is ViM 7.0, I see the desired line prepended by its line number. The mystery deepens. Smilie

Perhaps it's related to your ex/vi rc file. What if you use /5555/-2p?

Regards,
Alister

Last edited by alister; 07-24-2012 at 02:51 PM..
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