Using sed to replace first n lines in a file with the first n lines from another file (say n=5)

sed

I am trying to replace lines from one file (file1) with the same number of lines and in same positions from another file(file2). I found

sed -n 1,5p file2

would extract the first five lines from file2.
How can i use these lines and replace the first five lines in file1?

Best Answer

Bit of a cheat, (not pure sed), using sponge:

{ sed -n 1,5p file2 ; sed -n '6,$p' file1 } | sponge file1

Related Solutions

Replace lines matching a pattern with lines from another file in order

Easy can be done with awk

awk '
    /^!!/{                    #for line stared with `!!`
        getline <"file2.txt"  #read 1 line from outer file into $0 
    }
    1                         #alias for `print $0`
    ' file1.txt

Other version

awk '
    NR == FNR{         #for lines in first file
        S[NR] = $0     #put line in array `S` with row number as index 
        next           #starts script from the beginning
    }
    /^!!/{             #for line stared with `!!`
        $0=S[++count]  #replace line by corresponded array element
    }
    1                  #alias for `print $0`
    ' file2.txt file1.txt

Best Answer

Related Solutions

Replace lines matching a pattern with lines from another file in order

Related Question