Shell sed删除所有内容，而不是更改单个字段

嗨，我有这个代码，是要更新一个单一的领域标题，但它结束了它删除一切。需要帮忙吗

BookDB.txt：

The Hunger Games:Suzanne Collins:1:1:1 Weapon X:Stan Lee:1:1:1 Weapon X:stan lim:1:1:1 修订问题的答覆 需要更改

sed

命令，因为标题在第一行，而不是作者。由于如下所述的相同原因，删除了

tee

命令。因此，定义函数如下：

update_title () 
{ 
    echo "Title: ";
    read title;
    echo "Author: ";
    read author;
    grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!";
    echo "New Title: ";
    read title_new;
    sed -i "/:$author:/ s/^$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

例如，调用函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

结果是：

$ cat BookDB.txt 
The Hunger Games:Suzanne Collins:1:1:1
Weapon XYZ:Stan Lee:1:1:1
Weapon X:stan lim:1:1:1

原问题的答案 替换：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt || tee BookDB.txt && echo "Book Title has been updated sucessfully!"

为此：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

第一行要求

sed

就地重写

BookDB.txt

。然后它要求

tee

覆盖同一文件。解决办法是只做第一件事

解释 命令，例如：

sed 's/old/new/' file >file

或：

这将是不可靠的。它们试图在写入文件的同时读取文件。根据文件的缓冲方式，这种类型的命令可能偶尔会工作，但永远不可信

sed-i

是专门为避免此问题而设计的。它写入临时文件，并在成功保存所有更改后覆盖源文件

例子 让我们定义这个函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

现在，让我们使用它：

$ cat BookDB.txt 
Tim:Old Title:
Tom:Older Title:
$ update_title 
Title: 
Old Title
Author: 
Tim
New Title: 
New Title
Book Title has been updated sucessfully!
$ cat BookDB.txt 
Tim:New Title:
Tom:Older Title:

旧标题已成功替换

警告 此函数将shell变量直接替换为

sed

命令。如果用户不知道sed活动字符的威力，结果可能会令人惊讶

例如：

$ update_title 
Title: 
.*
Author: 
Tim
New Title: 
This & That
Book Title has been updated sucessfully!

现在，观察新文件：

$ cat BookDB.txt 
This Tim:New Title: That
Tom:Older Title:

OSX 在OSX上，sed的

-i

选项需要一个参数。对于OSX和可能的其他BSD平台，将函数定义中的

sed

行替换为：

   sed -i .bak "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

或者

修订问题的答覆 需要更改

sed

命令，因为标题在第一行，而不是作者。由于如下所述的相同原因，删除了

tee

命令。因此，定义函数如下：

update_title () 
{ 
    echo "Title: ";
    read title;
    echo "Author: ";
    read author;
    grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!";
    echo "New Title: ";
    read title_new;
    sed -i "/:$author:/ s/^$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

例如，调用函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

结果是：

$ cat BookDB.txt 
The Hunger Games:Suzanne Collins:1:1:1
Weapon XYZ:Stan Lee:1:1:1
Weapon X:stan lim:1:1:1

原问题的答案 替换：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt || tee BookDB.txt && echo "Book Title has been updated sucessfully!"

为此：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

第一行要求

sed

就地重写

BookDB.txt

。然后它要求

tee

覆盖同一文件。解决办法是只做第一件事

解释 命令，例如：

sed 's/old/new/' file >file

或：

这将是不可靠的。它们试图在写入文件的同时读取文件。根据文件的缓冲方式，这种类型的命令可能偶尔会工作，但永远不可信

sed-i

是专门为避免此问题而设计的。它写入临时文件，并在成功保存所有更改后覆盖源文件

例子 让我们定义这个函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

现在，让我们使用它：

$ cat BookDB.txt 
Tim:Old Title:
Tom:Older Title:
$ update_title 
Title: 
Old Title
Author: 
Tim
New Title: 
New Title
Book Title has been updated sucessfully!
$ cat BookDB.txt 
Tim:New Title:
Tom:Older Title:

旧标题已成功替换

警告 此函数将shell变量直接替换为

sed

命令。如果用户不知道sed活动字符的威力，结果可能会令人惊讶

例如：

$ update_title 
Title: 
.*
Author: 
Tim
New Title: 
This & That
Book Title has been updated sucessfully!

现在，观察新文件：

$ cat BookDB.txt 
This Tim:New Title: That
Tom:Older Title:

OSX 在OSX上，sed的

-i

选项需要一个参数。对于OSX和可能的其他BSD平台，将函数定义中的

sed

行替换为：

   sed -i .bak "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

或者

修订问题的答覆 需要更改

sed

命令，因为标题在第一行，而不是作者。由于如下所述的相同原因，删除了

tee

命令。因此，定义函数如下：

update_title () 
{ 
    echo "Title: ";
    read title;
    echo "Author: ";
    read author;
    grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!";
    echo "New Title: ";
    read title_new;
    sed -i "/:$author:/ s/^$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

例如，调用函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

结果是：

$ cat BookDB.txt 
The Hunger Games:Suzanne Collins:1:1:1
Weapon XYZ:Stan Lee:1:1:1
Weapon X:stan lim:1:1:1

原问题的答案 替换：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt || tee BookDB.txt && echo "Book Title has been updated sucessfully!"

为此：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

第一行要求

sed

就地重写

BookDB.txt

。然后它要求

tee

覆盖同一文件。解决办法是只做第一件事

解释 命令，例如：

sed 's/old/new/' file >file

或：

这将是不可靠的。它们试图在写入文件的同时读取文件。根据文件的缓冲方式，这种类型的命令可能偶尔会工作，但永远不可信

sed-i

是专门为避免此问题而设计的。它写入临时文件，并在成功保存所有更改后覆盖源文件

例子 让我们定义这个函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

现在，让我们使用它：

$ cat BookDB.txt 
Tim:Old Title:
Tom:Older Title:
$ update_title 
Title: 
Old Title
Author: 
Tim
New Title: 
New Title
Book Title has been updated sucessfully!
$ cat BookDB.txt 
Tim:New Title:
Tom:Older Title:

旧标题已成功替换

警告 此函数将shell变量直接替换为

sed

命令。如果用户不知道sed活动字符的威力，结果可能会令人惊讶

例如：

$ update_title 
Title: 
.*
Author: 
Tim
New Title: 
This & That
Book Title has been updated sucessfully!

现在，观察新文件：

$ cat BookDB.txt 
This Tim:New Title: That
Tom:Older Title:

OSX 在OSX上，sed的

-i

选项需要一个参数。对于OSX和可能的其他BSD平台，将函数定义中的

sed

行替换为：

   sed -i .bak "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

或者

修订问题的答覆 需要更改

sed

命令，因为标题在第一行，而不是作者。由于如下所述的相同原因，删除了

tee

命令。因此，定义函数如下：

update_title () 
{ 
    echo "Title: ";
    read title;
    echo "Author: ";
    read author;
    grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!";
    echo "New Title: ";
    read title_new;
    sed -i "/:$author:/ s/^$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

例如，调用函数：

$ update_title 
Title: 
Weapon X
Author: 
Stan Lee
Book Found!
New Title: 
Weapon XYZ
Book Title has been updated sucessfully!

function update_title
{
   echo "Title: "
   read title
   echo "Author: "
   read author
   grep -iqs "$title:$author:" BookDB.txt && echo "Book Found!"
   echo "New Title: "
   read title_new   
   sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"
}

结果是：

$ cat BookDB.txt 
The Hunger Games:Suzanne Collins:1:1:1
Weapon XYZ:Stan Lee:1:1:1
Weapon X:stan lim:1:1:1

原问题的答案 替换：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt || tee BookDB.txt && echo "Book Title has been updated sucessfully!"

为此：

sed -i "/^$author:/ s/$title/$title_new/" BookDB.txt && echo "Book Title has been updated sucessfully!"

第一行要求

sed

就地重写

BookDB.txt

。然后它要求

tee

覆盖同一文件。解决办法是只做第一件事

解释 命令，例如：

sed 's/old/new/' file >file

或：

这将是不可靠的。它们试图在写入文件的同时读取文件。根据文件的缓冲方式，这种类型的命令可能偶尔会工作，但永远不可信

sed-i

是专门为避免此问题而设计的。它写入一个临时文件，并在成功保存所有更改后