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我希望从变量$cpySold中减去$a[3]并添加到$a[4]. 我该怎么做？

目前我的输出如下：

Title:Alice in wonderland
Author:robert
No Of Copies Sold:*3*

Current Book Info:
Alice in wonderland, robert,$12.40,100,200

我该如何做下面的行？假设 100- 3 = 97, 100+ 3 = 103 在用户输入3份后售出。

新书信息：爱丽丝梦游仙境，罗伯特，12.40,97,203 美元

function process_book_sold
{
    read -p "Title: " title
    read -p "Author: " author
    read -p "No Of Copies Sold : " cpySold 
    if [ -n "$title" -a -n "$author" ]; then
    perl -ne 'BEGIN{ $pattern = $ARGV[0]; shift;$pattern1 = $ARGV[0]; shift; $n=0 }
    @a=split /:/;
    if ($a[0] =~ m/$pattern/i and $a[1] =~ m/$pattern1/i) 
    {
         print "Current Book Info: \n";
         print "$a[0], $a[1],\$$a[2],$a[3],$a[4]\n";
    }
    END{ print "\n" }' "$title" "$author" /home/student/Downloads/BookDB.txt
    fi
}
4

1 回答 1

0

我不喜欢在代码中混合使用 shell 和 Perl，但这显然是出于教学原因，所以我们不得不忽略它。

process_book_sold()
{
    read -p "Title: " title
    read -p "Author: " author
    read -p "No Of Copies Sold : " cpySold 
    if [ -n "$title" -a -n "$author" ]; then
        perl -ne '
            BEGIN{ $title = shift; $author = shift; $sales = shift; }
            @a = split /:/;
            if ($a[0] =~ m/$title/i and $a[1] =~ m/$author/i) 
            {
                 print "Current Book Info:\n";
                 print "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
                 $a[3] -= $sales;
                 $a[4] += $sales;
                 print "New Book Info:\n";
                 print "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
            }
            END{ print "\n" }' "$title" "$author" "$cpySold" /home/student/Downloads/BookDB.txt
    fi
}

除了重命名patterntotitle和pattern1to之外author，此代码还将 shell 变量传递$cpySold给 Perl。它还使用一种更简单的方法来检索前三个参数（只需从 中捕获值shift）。和split以前一样。数据文件中的格式是什么并不完全清楚，因为打印的格式使用逗号而不是冒号来分隔字段。

我只是希望新书信息中的值替换BookDB.txt文件中的当前书信息。

我不相信这对你有任何好处（除非你自己尝试做，否则你不会学到很多东西），但是......

process_book_sold()
{
    title="$1"
    author="$2"
    cpySold="$3"
    if [ -n "$title" -a -n "$author" ]
    then
        perl -i -we '
            use strict;
            use English "-no_match_vars";
            my $title = shift;
            my $author = shift;
            my $sales = shift;
            while (<>)
            {
                chomp;
                my @a = split /:/;
                print STDERR "Debug: @a\n";
                if ($a[0] =~ m/$title/i and $a[1] =~ m/$author/i) 
                {
                    print STDERR "Current Book Info:\n";
                    print STDERR "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
                    $a[3] -= $sales;
                    $a[4] += $sales;
                    print STDERR "New Book Info:\n";
                    print STDERR "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
                    $OFS = ":";
                    $ORS = "\n";
                    print @a;
                }
            }
            ' "$title" "$author" "$cpySold" BookDB.txt # /home/student/Downloads/BookDB.txt
    fi
}

#   read -p "Title: " title
#   read -p "Author: " author
#   read -p "No Of Copies Sold : " cpySold 
process_book_sold "Alice in Wonderland" "Carroll" "3"

这不会困扰我输入标题、作者或已售出的副本数量。如果您愿意，您可以恢复这些行，但如果该函数接受参数，它可能更有用。（将用户交互与操作文件的代码分开通常很好。）我使用了正确的作者姓名（除非您想使用 Dodgson 作为使用化名 Lewis Carroll 的作者的真实姓名）。Perl 脚本使用-i选项来覆盖输入文件。它使用English模块，因此它可以设置$OFS和$ORS。它将调试信息写入 STDERR（否则，它将是写入文件的信息的一部分）。

调用文件时pbs2.sh，脚本的示例运行如下所示：

$ cat BookDB.txt; bash pbs2.sh; cat BookDB.txt
Alice in Wonderland:Carroll:$12.40:74:226
Debug: Alice in Wonderland Carroll $12.40 74 226
Current Book Info:
Alice in Wonderland, Carroll, $12.40, 74, 226
New Book Info:
Alice in Wonderland, Carroll, $12.40, 71, 229
Alice in Wonderland:Carroll:$12.40:71:229
$

显然，这不是我第一次运行该脚本，而且有时我使用 3 以外的值来表示已售出的副本数量。

通过显式文件管理，您可以编写：

process_book_sold()
{
    title="$1"
    author="$2"
    cpySold="$3"
    if [ -n "$title" -a -n "$author" ]; then
        perl -we '
            use strict;
            use English "-no_match_vars";
            my $title = shift;
            my $author = shift;
            my $sales = shift;
            my $file = shift;
            open my $fh, "+<", $file or die "Failed to open file $file for reading and writing";
            my $text;
            {
            local $/;
            $text = <$fh>;
            }
            chomp $text;
            my @a = split /:/, $text;
            print "Debug: @a\n";
            if ($a[0] =~ m/$title/i and $a[1] =~ m/$author/i) 
            {
                print "Current Book Info:\n";
                print "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
                $a[3] -= $sales;
                $a[4] += $sales;
                print "New Book Info:\n";
                print "$a[0], $a[1], $a[2], $a[3], $a[4]\n";
                seek $fh, 0, 0;
                truncate $fh, 0;
                $OFS = ":";
                $ORS = "\n";
                print $fh @a;
            }
            close $fh;
            ' "$title" "$author" "$cpySold" BookDB.txt # /home/student/Downloads/BookDB.txt
    fi
}

# read -p "Title: " title
# read -p "Author: " author
# read -p "No Of Copies Sold : " cpySold 

process_book_sold "Alice in Wonderland" "Carroll" "7"

样品运行：

$ cat BookDB.txt; bash pbs1.sh; cat BookDB.txt
Alice in Wonderland:Carroll:$12.40:50:250
Debug: Alice in Wonderland Carroll $12.40 50 250
Current Book Info:
Alice in Wonderland, Carroll, $12.40, 50, 250
New Book Info:
Alice in Wonderland, Carroll, $12.40, 43, 257
Alice in Wonderland:Carroll:$12.40:43:257
$
于 2013-08-04T21:27:26.870 回答