select subdomains using print command-CodePudding

cat a.txt

a.b.c.d.e.google.com
x.y.z.google.com

rev a.txt | awk -F. '{print $2,$3}' | rev

This is showing:

e google
x google

But I want this output

a.b.c.d.e.google
b.c.d.e.google
c.d.e.google
e.google
x.y.z.google
y.z.google
z.google

Thank You in Advance

CodePudding user response：

Here is one more awk solution:

awk -F. '{while (!/^[^.] \.[^.] $/) {print; sub(/^[^.] \./, "")}}' file

a.b.c.d.e.google.com
b.c.d.e.google.com
c.d.e.google.com
d.e.google.com
e.google.com
x.y.z.google.com
y.z.google.com
z.google.com

CodePudding user response：

With your shown samples, please try following awk code. Written and tested in GNU awk should work in any awk.

awk '
BEGIN{
  FS=OFS="."
}
{
  nf=NF
  for(i=1;i<(nf-1);i  ){
    print
    $1=""
    sub(/^[[:space:]]*\./,"")
  }
}
' Input_file

CodePudding user response：

Using sed

$ sed -n '/^/p;:a;s/[a-z]*\.\(.*[a-z]\.[a-z]*\.[a-z]*\)/\1/p;ta;' input_file
a.b.c.d.e.google.com
b.c.d.e.google.com
c.d.e.google.com
d.e.google.com
e.google.com
x.y.z.google.com
y.z.google.com
z.google.com

CodePudding user response：

Using bash:

IFS=.
while read -ra a; do
    for ((i=${#a[@]}; i>2; i--)); do
        echo "${a[*]: -i}"
    done
done < a.txt

Gives:

a.b.c.d.e.google.com
b.c.d.e.google.com
c.d.e.google.com
d.e.google.com
e.google.com
x.y.z.google.com
y.z.google.com
z.google.com

(I assume the lack of d.e.google.com in your expected output is typo?)