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如何 awk 唯一行并打印上面 2 行

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如何 awk 唯一行并打印上面 2 行

我遇到一个问题，我使用 awk 查找一行并在上面打印两行

文件 test.txt 文件内如下”

{ TABLE "sacro".issue row size = 149 number of columns = 9 index size = 0 }

{ unload file name = issue00106.unl number of rows = 74 }

create table "sacro".issue
( 
issue_no serial not null constraint "sacro".nnc_issue00,
user_logged varchar(8,1) not null constraint "sacro".nnc_issue01,
issue_status_code integer not null constraint "sacro".nnc_issue02,
issue_cat_code varchar(2) not null constraint "sacro".nnc_issue03,
issue_descr text not null constraint "sacro".nnc_issue04,
issue_feedback text,
user_action varchar(8,1),
date_logged date not null constraint "sacro".nnc_issue05,
date_compl date
);

revoke all on "sacro".issue from "public" as "sacro";

{ TABLE "sacro".issue_category row size = 104 number of columns = 2 index                        size = 8 }

{ unload file name = issue00107.unl number of rows = 5 }

create table "sacro".issue_category
(
issue_cat_code varchar(2) not null constraint "sacro".nnc_iss_cat00,
issue_cat_descr varchar(100),
primary key (issue_cat_code)  constraint "sacro".pkc_issuecategory
);

revoke all on "sacro".issue_category from "public" as "sacro";

{ TABLE "sacro".issue row size = 149 number of columns = 9 index size = 0 }

{ unload file name = issue00106.unl number of rows = 74 }

我正在搜索的行如下：

create table "sacro".issue

我正在运行的命令是：

cat test.txt | awk '{a[NR]=$0} $0~s {f=NR} END {for (i=f-B;i<=f+A;i++) print a[i]}' B=2 A=0 s='create table \"sacro\".issue'

当我运行该命令时，它找到行 create table "sacro".issue_category。有没有办法 grep 查找我需要的行，就像我使用 grep -w 一样。不幸的是，下面的 grep 命令在 HPUX 上不起作用：

cat test.txt | grep -B 2 -w "create table \"sacro\".issue" | head -1

我想要的结果应该是（使用头-1）：

{ unload file name = issue00106.unl number of rows = 74 }

答案1

sed -e '
   1N                                  # get 2nd line in pattern space
   $!N                                 # get 3rd line in pattern space
   /\ncreate table "sacro"\.issue$/P   # if the last portion of matches, show 1st portion
   D                                   # strip 1st portion & reapply sed code on what
                                       # remains of the pattern space
' test.txt

grep -B 2 'create table "sacro"\.issue$' test.txt | sed q

答案2

首先，没有理由grep不能这样做。哦，请注意，您不需要cat, 和 都grep可以awk接受输入文件名：

$ grep -xB2 'create table "sacro".issue' file
{ unload file name = issue00106.unl number of rows = 74 }

create table "sacro".issue

因此，如果您只想要第一行，请执行以下操作：

$ grep -xB2 'create table "sacro".issue' file | head -n1
{ unload file name = issue00106.unl number of rows = 74 }

这-x意味着“匹配整行”，确保create table "sacro".issue_category不打印该行。意思-B2是“同时打印前两行。

awk您也可以按照要求进行：

$ awk -vs='create table "sacro".issue' '($0==s){print b2}{b2=b1; b1=$0}' file 
{ unload file name = issue00106.unl number of rows = 74 }

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