Shell Programming and Scripting

awk 'NR==FNR {m[$1]=$0; next} $1 in m{$0=m[$1]} {print}' file2 file1

The Man on the moon 1
The Man on Jupiter 2
The Man on Mars 3
The Man on Earth 4

The Man on the moon 1        https://www.example1.com/
The Man on Jupiter 2        https://www.example2.com/
The Man on Mars 3       https://www.example3.com/

awk 'NR==FNR {m[$1]=$0; next} $1 in m{$0=m[$1]} {print}' file2 file1

The Man on Mars 3        https://www.example3.com/
The Man on Mars 3        https://www.example3.com/
The Man on Mars 3       https://www.example3.com/
The Man on Mars 3        https://www.example3.com/
<empty line>

The Man on the moon 1        https://www.example1.com/
The Man on Jupiter 2        https://www.example2.com/
The Man on Mars 3       https://www.example3.com/
The Man on Earth 4       Not Available

awk -F'\t' '
        NR == FNR {
                m[$1] = $0
                next
        }
        {
                if ( $1 in m )
                        $0 = m[$1]
                else
                        $0 = $1 OFS "Not Available"
                print
        }
' OFS='\t' file2 file1

awk 'FNR==NR{Q=$NF;$NF="";gsub(/[[:space:]]+$/,X,$0);A[$0]=Q;next} {Q=($0 in A)?$0 OFS A[$0]:$0 OFS "NA";print Q;Q=""}' file2 file1

awk: cmd. line:1: NR == FNR {m[$1] = $0; next} {if ( $1 in m )$0 = m[$1] else $0 = $1 OFS "Not Available"}
awk: cmd. line:1:                                                        ^ syntax error

awk -F"\t" '
NR == FNR       {m[$1] = $NF
                 next
                }
!($1 in m)      {m[$1] = "Not Available"
                }
                {$(NF+1) =  m[$1]
                }
1
' OFS='\t' file2 file1

awk -F'\t' 'NR==FNR{m[$1]=$0;next}{if($1 in m) $0=m[$1];else $0=$1 OFS "Not Available";print}' OFS='\t' file2 file1