什么是＆QUOT意义; 0 / XXX＆QUOT;在sed？ [英] What is the meaning of "0,/xxx" in sed?
问题描述
在脚本中使用的sed命令如下：
A sed command used in a script as following:
sed -i "0,/^ENABLE_DEBUG.*/s/^ENABLE_DEBUG.*/ENABLE_DEBUG = YES/" MakeConfig
我知道
s/^ENABLE_DEBUG.*/ENABLE_DEBUG = YES/
是替代线preFIX
is to substitutes line prefix
ENABLE_DEBUG 为 ENABLE_DEBUG = YES
但没有关于意义的想法
0,/^ENABLE_DEBUG.*/
任何人都可以帮我吗？
Anyone can help me?
推荐答案
0，/ ^ ENABLE_DEBUG。* / 指取代只会从一开始线路发生， 0 ，到与其匹配的第一行 / ^ ENABLE_DEBUG。* / 。没有替代将在后续的行作出，即使它们匹配 / ^ ENABLE_DEBUG。* /
0,/^ENABLE_DEBUG.*/ means that the substitution will only occur on lines from the beginning, 0, to the first line that matches /^ENABLE_DEBUG.*/. No substitution will be made on subsequent lines even if they match /^ENABLE_DEBUG.*/
这将只行2至5代：
sed '2,5 s/old/new/'
这将取代从第2行，第一行就包括在的东西：
This will substitute from line 2 to the first line after it which includes something:
sed '2,/something/ s/old/new/'
这将包含的东西到文件末尾的第一行替换：
This will substitute from the first line that contains something to the end of the file:
sed '/something/,$ s/old/new/'
POSIX与GNU范围：线路为0
的意义考虑这个测试文件：
POSIX vs. GNU ranges: the meaning of line "0"
Consider this test file:
$ cat test.txt
one
two
one
three
现在，让我们应用SED在范围 1，/一个/ ：
Now, let's apply sed over the range 1,/one/:
$ sed '1,/one/ s/one/Hello/' test.txt
Hello
two
Hello
three
范围与1号线开始，以之后的第一行的结尾匹配行1 有一个。因此，两个换人上面的。
The range starts with line 1 and ends with the first line after line 1 that matches one. Thus two substitutions are made above.
假设我们只想在第一个有一个替换。符合POSIX sed的，这不能与范围进行。由于NeronLeVelu指出，GNU SED提供了这种情况下的扩展：它允许我们指定范围为 0，/一个/ 。该范围内第一次出现的结束有一个中的文件：
Suppose that we only wanted the first one replaced. With POSIX sed, this cannot be done with ranges. As NeronLeVelu points out, GNU sed offers an extension for this case: it allows us to specify the range as 0,/one/. This range ends with the first occurrence of one in the file:
$ sed '0,/one/ s/one/Hello/' test.txt
Hello
two
one
three
因此，范围 0，/ ^ ENABLE_DEBUG / 有与 ENABLE_DEBUG 开头的第一线，即使结束该行是第一行。这需要GNU sed的。
Thus, the range 0,/^ENABLE_DEBUG/ ends with the first line that begins with ENABLE_DEBUG even if that line is the first line. This requires GNU sed.
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