Pertahankan Hanya Baris Pertama Dari Setiap Urutan Garis Berturut-turut yang Cocok dengan Pola?

Jika 2 atau lebih baris berurutan berisi pola tertentu, hapus semua baris yang cocok dan pertahankan hanya baris pertama.

Dalam contoh di bawah ini ketika 2 atau lebih baris berturut-turut mengandung “logical IO” maka kita perlu menghapus semua baris yang cocok tetapi tetap mempertahankan baris pertama.

Berkas masukan:

select * from test1 where 1=1
testing logical IO 24
select * from test2 where condition=4
parsing logical IO 45
testing logical IO 500
handling logical IO 49
select * from test5 where 1=1
testing logical IO 24
select * from test5 where condition=78
parsing logical IO 346
testing logical IO 12

Berkas keluaran:

select * from test1 where 1=1
testing logical IO 24
select * from test2 where condition=4
parsing logical IO 45
select * from test5 where 1=1
testing logical IO 24
select * from test5 where condition=78
parsing logical IO 346

Jawaban yang Diterima:

Menggunakan awk :

awk '/logical IO/ {if (!seen) {print; seen=1}; next}; {print; seen=0}' file.txt 

• /logical IO/ {if (!seen) {print; seen=1}; next} memeriksa apakah baris berisi logical IO , jika ditemukan dan variabel seen salah yaitu baris sebelumnya tidak mengandung logical IO , lalu cetak baris, setel seen=1 dan lanjutkan ke baris berikutnya jika tidak, lanjutkan ke baris berikutnya karena baris sebelumnya memiliki logical IO

• Untuk baris lainnya, {print; seen=0} , mencetak baris dan set seen=0

Contoh:

$ cat file.txt 
select * from test1 where 1=1
testing logical IO 24
select * from test2 where condition=4
parsing logical IO 45
testing logical IO 500
select * from test5 where 1=1
testing logical IO 24
select * from test5 where condition=78
parsing logical IO 346
parsing logical IO 346
testing logical IO 12

$ awk '/logical IO/ {if (!seen) {print; seen=1}; next}; {print; seen=0}' file.txt 
select * from test1 where 1=1
testing logical IO 24
select * from test2 where condition=4
parsing logical IO 45
select * from test5 where 1=1
testing logical IO 24
select * from test5 where condition=78
parsing logical IO 346