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Modify file without passing o/p to new file

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# 8  
Old 12-23-2013
There is always the straightforward ed or ex that you can use to edit a file:
Code:
ed -s file <<-EOF
        g/Pattern to delete/d
        w
        q
EOF

Leave off the -s option if you want to see the size of the file as it is read in and as it is written after deleting the matched lines.
This User Gave Thanks to Don Cragun For This Post:
Roozo
# 9  
Old 12-23-2013
Hi.
Quote:
Originally Posted by drl
See also thread Delete first 100 lines from a BIG File for several comments, approaches (and reproaches) to problems of this kind.

One theme is a utility sponge, a perl version of which I included as absorb-memory in post #6. It holds data in memory, writes to a file as you direct, and, because of the argument handling, it can preserve inodes writing to the input file in the pipeline (noted again, without using an intermediate scratch file). Note also that Scrutinizer and I tended to disagree on this approach, but you can decide if it is useful for you.
Note in thread Delete first 100 lines from a BIG File | Unix Linux Forums | UNIX for Advanced & Expert Users that at least some versions of ed/ex will use a scratch file.

Best wishes ... cheers, drl
# 10  
Old 01-07-2014
How to find and replace using this below methods ??

Code:
perl -i -n -e 'if(!/Pattern to delete/) {print}' file
 
 
ed -s file <<-EOF
        g/Pattern to delete/d
        w
        q
EOF

# 11  
Old 01-07-2014
Code:
ed -s file <<-EOF
        g/Pattern to find/s//replacement string/g
        w
        q
EOF

This User Gave Thanks to Don Cragun For This Post:
Roozo
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