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Help search and replace the last occurance of match in a file

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# 1  
Old 02-02-2018
DB Help search and replace the last occurance of match in a file
Hi I want to replace only the last occurance of "union all" in input file with ";"
I tried with sed 's/union all/;/g' in my input file, it replaced in all lines of input file

Eg:
Code:
select column1,column2 from test1 group by 2 union all
 select column1,column2 from test2 group by 2 union all
 select column1,column2 from test3 group by 2 union all

I need to replace only the last "union all" in the above with ";".

Thanks

Moderator's Comments:
Mod Comment Please use CODE tags as required by forum rules!
Last edited by RudiC; 02-03-2018 at 04:33 AM.. Reason: Added CODE tags.
# 2  
Old 02-02-2018
One way:
Code:
awk '{ arr[NR]=$0; index($0,"union all")>0  {L=NR} }
END { gsub(/union all/, "", arr{L})
          for(i=0; i<NT; i++) 
                    {print arr[i])
        }'  infile > outfile

There are some errors in the above - thanks Rudi.
See new post below
Last edited by jim mcnamara; 02-03-2018 at 10:13 AM..
This User Gave Thanks to jim mcnamara For This Post:
antosr7
# 3  
Old 02-03-2018
Another way:
Code:
ed -s infile <<-EOF
	?union all?s//;/
	w outfile
	q
EOF

where infile and outfile, respective, are pathnames to your input and output files.

You can just use:
Code:
	w

instead of:
Code:
	w outfile

if you want to update your input file instead of creating a new output file.
This User Gave Thanks to Don Cragun For This Post:
antosr7
# 4  
Old 02-03-2018
Thanks for the reply Don cragun
I am working on centos in which ed command not found
# 5  
Old 02-03-2018
Hi antosr7,

This may be one of the methods:
Code:
grep "test3" <input_filename> | sed "s/ union all/;/"

where the test3 is the keyword to extract the line and the <filename> is where the three lines can be found.

Hope that this is helpful.

Thank you.
This User Gave Thanks to JiaHong For This Post:
antosr7
# 6  
Old 02-03-2018
Quote:
Originally Posted by antosr7
Thanks for the reply Don cragun
I am working on centos in which ed command not found
Does Centos have the ex utility? If so, for the features I used in the ed script in post #3, ex will work the same way with the same options. On UNIX, Linux, and BSD systems, I usually use ed instead of ex because ex is usually larger and slower to load than ed. The ex utility is bigger because it supplies some extra features that ed doesn't provide, but they aren't used in this script.
This User Gave Thanks to Don Cragun For This Post:
antosr7
# 7  
Old 02-03-2018
Code:
# expanded lines and fixed errors
awk '{ arr[NR]=$0; 
       if (index($0,"union all")>0)  
       {L=NR} 
     }
END { 
      gsub(/union all/, "", arr[L])
      for(i=0; i<NR; i++) 
             {print arr[i] }
    }'  infile > outfile

This User Gave Thanks to jim mcnamara For This Post:
antosr7
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