How to get only the first occurrence of the pattern in bash script

Question

Hi All can you please help me I am trying to get the following output so basically I have 2 input files and we need only the common :names from both the input files along with there the lines below them the .name/of/file lines.

Till now I have tried:

awk 'FNR==NR { a[$1]; next }NF<=1   { flag=0   } $1 in a { flag=1   }flag' file1 file2

Output:

:name1
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
:name3
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
:name1
    ./name/of/file [logfile] [ error in file coming since Day : 40]
    ./name/of/file [logfile] [ error in file coming since Day : 40 ]
:name4
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]

:name4
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]

But its printing all the occrance of :name1 and :name4 we only need the first occurrence of :name1 and :name4 from input file 1

Input file1:

:name1
./name/of/file [logfile] [ error in file coming since Day : 1 ]
./name/of/file [logfile] [ error in file coming since Day : 1 ]

:name2
./name/of/file [logfile] [ error in file coming since Day : 1 ]

:name3
./name/of/file [logfile] [ error in file coming since Day : 24 ]
./name/of/file [logfile] [ error in file coming since Day : 24 ]

 :name1
./name/of/file [logfile] [ error in file coming since Day : 40]
./name/of/file [logfile] [ error in file coming since Day : 40 ]

:name4
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]

:name5
./name/of/file [logfile] [ error in file coming since Day : 6 ]
./name/of/file [logfile] [ error in file coming since Day : 6 ]

:name4
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]
./name/of/file [logfile] [ error in file coming since Day : 10 ]  

Input file2:

:name1
:name3
:name4

Required Outputfile:

:name1
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
:name3
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
:name4
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]

Answer 1

Since an 'occurrence' is based on the name existing as an index in the a[] array, removal of that entry from the array should disable any further 'occurrences'.

We can accomplish this removal by adding a delete to the current awk code:

awk '
FNR==NR { a[$1]; next          }
NF<=1   { flag=0               }      # clear flag if zero or one non-white-space fields is present in the current line
$1 in a { flag=1; delete a[$1] }      # set flag if 1st field is an index in the a[] array; delete entry from array to insure no more occurrences of this name ($1)
flag                                  # if flag == 1 then print current line to stdout
' file2 file1

This generates:

:name1
./name/of/file [logfile] [ error in file coming since Day : 1 ]
./name/of/file [logfile] [ error in file coming since Day : 1 ]
:name3
./name/of/file [logfile] [ error in file coming since Day : 24 ]
./name/of/file [logfile] [ error in file coming since Day : 24 ]
:name4
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]
./name/of/file [logfile] [ error in file coming since Day : 3 ]

---

If the logfile lines need to be indented (eg, 4 spaces as in the question), one idea:

awk '
FNR==NR { a[$1]; next }
NF<=1   { flag=0 }
$1 in a { print; flag=1; delete a[$1]; next }
flag    { printf "    %s\n",$0 }
' file2 file1

This generates:

:name1
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
    ./name/of/file [logfile] [ error in file coming since Day : 1 ]
:name3
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
    ./name/of/file [logfile] [ error in file coming since Day : 24 ]
:name4
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]
    ./name/of/file [logfile] [ error in file coming since Day : 3 ]