CODEWITHSUNDEEP
regexlinuxsed
Satish
Satish

Reputation: 17467

sed replace second last line of file

I want to replace second last line of file, I know $ use for last line but don't know how to say second line from end. 

parallel (
{
ignore(FAILURE) {
build( "Build2Test", BUILDFILE: "", WARFILE: "http://maven.example.com/130602.0.war", STUDY: "UK", BUG: "33323" )
}},
)

I want to replace }}, with }} in short i want to remove , comma but this file has many other codes so i can't use pattern match i need to use second line from end of file.

Upvotes: 4

Views: 6330

Answers (4)

clt60
clt60

Reputation: 63974

If you know, how to change N-th line, simply reverse the the file first, e.g. It is not as much professional as the other sed solutions, but works... :)

tail -r <file | sed '2s/}},/}}/' | tail -r >newfile

e.g. from the next input

}},
}},
}},
}},
}},

the above makes

}},
}},
}},
}}
}},

The tail -r are BSD equivalent of Linux's tac command. On Linux use tac on OS X or Freebsd use tail -r. Bot doing the same: prints the file in reveresed order of lines (last line prints as first).

Upvotes: 7

glenn jackman
glenn jackman

Reputation: 247200

reverse the file, work on the 2nd line, then re-reverse the file:

tac file | sed '2 s/,$//' | tac

to save the result back to "file", add this to the command

 > file.new && mv file file.bak && mv file.new file

Or, use an ed script

ed file <<END
$-1 s/,$//
w
q
END

Upvotes: 6

potong
potong

Reputation: 58568

This might work for you (GNU sed):

sed '$!N;$s/}},/}}/;P;D' file

Keep two lines in the pattern space and at-end-of-file substitute the required pattern.

Upvotes: 3

Andrew Clark
Andrew Clark

Reputation: 208665

The following should work (note that on some systems you may need to remove all of the comments):

sed '1 {        # if this is the first line
  h               # copy to hold space
  d               # delete pattern space and return to start
}
/^}},$/ {       # if this line matches regex /^}},$/
  x               # exchange pattern and hold space
  b               # print pattern space and return to start
}
H               # append line to hold space
$ {             # if this is the last line
  x               # exchange pattern and hold space
  s/^}},/}}/      # replace "}}," at start of pattern space with "}}"
  b               # print pattern space and return to start
}
d               # delete pattern space and return to start'

Or the compact version:

sed '1{h;d};/^}},$/{x;b};H;${x;s/^}},/}}/;b};d'

Example:

$ echo 'parallel (
{
ignore(FAILURE) {
build( "Build2Test", BUILDFILE: "", WARFILE: "http://maven.example.com/130602.0.war", STUDY: "UK", BUG: "33323" )
}},
)' | sed '1{h;d};/^}},$/{x;b};H;${x;s/^}},/}}/;b};d'
parallel (
{
ignore(FAILURE) {
build( "Build2Test", BUILDFILE: "", WARFILE: "http://maven.example.com/130602.0.war", STUDY: "UK", BUG: "33323" )
}}
)

Upvotes: 7

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