我需要一个在GNU和BSD上都可以工作的解决方案，而且我也知道第一行永远不会是我需要更新的一行:

sed -e "1,/pattern/s/pattern/replacement/"

尝试//特性不重复模式对我不起作用，因此需要重复它。

 # sed script to change "foo" to "bar" only on the first occurrence
 1{x;s/^/first/;x;}
 1,/foo/{x;/first/s///;x;s/foo/bar/;}
 #---end of script---

或者，如果你喜欢:编辑注:只适用于GNU sed。

sed '0,/foo/s//bar/' file 

源

你可以使用awk来做类似的事情。

awk '/#include/ && !done { print "#include \"newfile.h\""; done=1;}; 1;' file.c

解释:

/#include/ && !done

当行匹配“#include”并且我们还没有处理它时，在{}之间运行操作语句。

{print "#include \"newfile.h\""; done=1;}

这将打印#include "newfile.h"，我们需要转义引号。然后我们将done变量设置为1，这样我们就不会添加更多的include。

1;

这意味着“打印出行”——一个空操作默认为打印$0，打印出整行。一个简单的程序，比sed更容易理解:-)

我将提出一个建议，这并不完全是最初的问题所要求的，但对于那些还想特别替换匹配的第二次出现，或任何其他特别枚举的正则表达式匹配的人来说。使用python脚本和for循环，如果需要从bash脚本调用它。这是它看起来像我，在我替换特定行包含字符串-项目:

def replace_models(file_path, pixel_model, obj_model):
    # find your file --project matches
    pattern = re.compile(r'--project.*')
    new_file = ""
    with open(file_path, 'r') as f:
        match = 1
        for line in f:
            # Remove line ending before we do replacement
            line = line.strip()
            # replace first --project line match with pixel
            if match == 1:
                result = re.sub(pattern, "--project='" + pixel_model + "'", line)
            # replace second --project line match with object
            elif match == 2:
                result = re.sub(pattern, "--project='" + obj_model + "'", line)
            else:
                result = line
            # Check that a substitution was actually made
            if result is not line:
                # Add a backslash to the replaced line
                result += " \\"
                print("\nReplaced ", line, " with ", result)
                # Increment number of matches found
                match += 1
            # Add the potentially modified line to our new file
            new_file = new_file + result + "\n"
        # close file / save output
        f.close()
    fout = open(file_path, "w")
    fout.write(new_file)
    fout.close()

这里可能的解决方案是告诉编译器包含头文件，而不在源文件中提到它。在GCC中有这些选项:

   -include file
       Process file as if "#include "file"" appeared as the first line of
       the primary source file.  However, the first directory searched for
       file is the preprocessor's working directory instead of the
       directory containing the main source file.  If not found there, it
       is searched for in the remainder of the "#include "..."" search
       chain as normal.

       If multiple -include options are given, the files are included in
       the order they appear on the command line.

   -imacros file
       Exactly like -include, except that any output produced by scanning
       file is thrown away.  Macros it defines remain defined.  This
       allows you to acquire all the macros from a header without also
       processing its declarations.

       All files specified by -imacros are processed before all files
       specified by -include.

微软的编译器有/FI(强制包含)选项。

这个特性对于一些常见的头文件来说很方便，比如平台配置。Linux内核的Makefile为此使用-include。

下面的命令删除文件中字符串的第一次出现。它还删除了空行。它显示在xml文件上，但它可以用于任何文件。

如果您使用xml文件并且想要删除一个标记，则非常有用。在本例中，它删除了第一次出现的“isTag”标记。

命令:

sed -e 0,/'<isTag>false<\/isTag>'/{s/'<isTag>false<\/isTag>'//}  -e 's/ *$//' -e  '/^$/d'  source.txt > output.txt

源文件:Source .txt

<xml>
    <testdata>
        <canUseUpdate>true</canUseUpdate>
        <isTag>false</isTag>
        <moduleLocations>
            <module>esa_jee6</module>
            <isTag>false</isTag>
        </moduleLocations>
        <node>
            <isTag>false</isTag>
        </node>
    </testdata>
</xml>

结果文件(output.txt)

<xml>
    <testdata>
        <canUseUpdate>true</canUseUpdate>
        <moduleLocations>
            <module>esa_jee6</module>
            <isTag>false</isTag>
        </moduleLocations>
        <node>
            <isTag>false</isTag>
        </node>
    </testdata>
</xml>

ps:它在Solaris SunOS 5.10(相当旧)上不能工作，但在Linux 2.6 sed版本4.1.5上可以工作