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grep不显示结果,在线regex测试仪显示结果

grep regex

slhck · 技术社区 · 15 年前

我对grep的行为相当没有经验。我有一堆XML文件,其中包含如下行:

<identifier type="abc">abc:def.ghi/g1234.ab012345</identifier>
<identifier type="abc">abc:def.ghi/g5678m.ab678901</identifier>

我想在斜杠后面得到标识符部分,并用 RegexPal :

[a-z]\d{4}[a-z]*\.[a-z]*\d*

它突出了我想要的一切。很完美。现在,当我在同一个文件上运行grep时,不会得到任何结果。正如我所说,我对grep的了解并不多,所以我尝试了所有不同的组合。

grep [a-z]\d{4}[a-z]*\.[a-z]*\d* test.xml
grep "[a-z]\d{4}[a-z]*\.[a-z]*\d*" test.xml
egrep "[a-z]\d{4}[a-z]*\.[a-z]*\d*" test.xml
grep '[a-z]\d{4}[a-z]*\.[a-z]*\d*' test.xml
grep -E '[a-z]\d{4}[a-z]*\.[a-z]*\d*' test.xml

我做错什么了?

7 回复 | 直到 7 年前

Meekohi 7 年前

[a-z] g
\d{4} 1234
[a-z]* .

grep \d [0-9] [:digit:]

egrep *

Kobi 15 年前

grep \d [0-9]

$ grep -P "[a-z]\d{4}[a-z]*\.[a-z]*\d*" test.xml

$ egrep "[a-z][0-9]{4}[a-z]*\.[a-z]*[0-9]*" test.xml

James Anderson 15 年前

Basic vs Extended Regular Expressions
   In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their
   special meaning; instead use the backslashed versions \?, \+, \{,  \|,  \(,  and
   \).

   Traditional  egrep  did  not  support  the  {  meta-character,  and  some  egrep
   implementations support \{ instead,  so  portable  scripts  should  avoid  {  in
   grep -E patterns and should use [{] to match a literal {.

   GNU  grep -E  attempts  to  support  traditional usage by assuming that { is not
   special if it would be the start of  an  invalid  interval  specification.   For
   example,  the  command  grep -E '{1'  searches  for  the two-character string {1
   instead of reporting a syntax error in the regular expression.   POSIX.2  allows
   this behavior as an extension, but portable scripts should avoid it.

codaddict 15 年前

$ cat file
<identifier type="abc">abc:def.ghi/g1234.ab012345</identifier>

# Use -P option to enable Perl style regex \d.
$ grep -P  '[a-z]\d{4}[a-z]*\.[a-z]*\d*' file
<identifier type="abc">abc:def.ghi/g1234.ab012345</identifier>

# to get only the part of the input that matches use -o option:
$ grep -P -o '[a-z]\d{4}[a-z]*\.[a-z]*\d*' file
g1234.ab012345

# You can use [0-9] inplace of \d and use -E option.
$ grep -E -o '[a-z][0-9]{4}[a-z]*\.[a-z]*[0-9]*' file
g1234.ab012345
$