difficult nawk to understand

ahmad.diab · #1 (**permalink**) 10-29-2008

I found a command who prints x lines before and after a line who contain a searched string in a text file.
The command is :

nawk 'c-->0;$0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}b{r[NR%b]=$0}' b=2 a=4 s="string" file1

It works very well but I can't understand the syntax, too difficult with "man nawk". Is that some one who will be able to comment this syntax ?

Thank's in advance.

Perderabo · #2 (**permalink**) 10-29-2008

See: nawk use

chihung · #3 (**permalink**) 10-29-2008

I will try to 'decipher' that one-liner awk code

Code:

awk -v before=4 -v after=4 -v search="string" '
--current > 0 {
        print
}
$0 ~ search{
        if ( before ) {
                for ( current=before+1 ; current>1 ; current-- ) {
                        print rec[(NR-current+1)%before]
                }
        }
        print
        current=after
}
before{
        rec[NR%before]=$0
}' file1

I think the above code is a lot easier to understand and pretty self explanatory, hopefully.
The original one-liner is taking a lot of shortcut and default.

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