筛选名称为时间戳的文件夹-使用find实用工具进行模式匹配与正则表达式匹配 [英] Filter folders whose name is a timestamp - pattern matching vs. regex matching using the find utility
问题描述
我正在编写一个通用的shell脚本，该脚本根据给定的正则表达式过滤掉文件.
I am writing a generic shell script which filters out files based on given regex.
我的shell脚本:
files=$(find $path -name $regex)
在一种情况下(要过滤)，我想过滤目录中的文件夹，文件夹名称采用以下格式:
In one of the cases (to filter), I want to filter folders inside a directory, the name of the folders are in the below format:
20161128-20:34:33:432813246
YYYYMMDD-HH:MM:SS:NS
我无法找到正确的正则表达式.
I am unable to arrive at the correct regex.
我可以使用正则表达式'*data.txt'获取文件夹中文件的路径，因为我知道其中的文件名.
I am able to get the path of the files inside the folder using the regex '*data.txt', as I know the name of the file inside it.
但是它为我提供了文件的完整路径，例如
But it gives me the full path of the file, something like
/path/20161128-20:34:33:432813246/data.txt
我想要的只是:
/path/20161128-20:34:33:432813246
请帮助我确定符合我要求的正确正则表达式
Please help me in identifying the correct regex for my requirement
注意:
我知道以后如何处理数据
I know how to process the data after
files=$(find $path -name $regex)
但是由于脚本在许多用例中都需要通用，因此我只需要正确的正则表达式即可.
But since the script needs to be generic for many use cases, I only need the correct regex that needs to be passed.
推荐答案
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根据POSIX ，
find-name-path主要(测试)使用 patterns (又称通配符表达式，glob)来匹配文件名和路径名(尽管模式和正则表达式之间有着遥远的联系，但它们的语法和功能却大不相同；简而言之:模式在语法上更简单，但功能远不如此.Per POSIX,
find's-name-pathprimaries (tests) use patterns (a.k.a wildcard expressions, globs) to match filenames and pathnames (while patterns and regular expressions are distantly related, their syntax and capabilities differ significantly; in short: patterns are syntactically simpler, but far less powerful).-
-name，并将模式与仅输入路径的 basename (仅文件名)部分匹配 -
-path将模式与整个 pathname (完整路径)匹配
-nameand matches the pattern against the basename (mere filename) part of an input path only-pathmatches the pattern against the whole pathname (the full path)
GNU和BSD/macOS
find都实现了非标准扩展:Both GNU and BSD/macOS
findimplement nonstandard extensions:-
-iname和-ipath与它们的标准兼容版本(基于 patterns )相似，但区别在于不区分大小写. >
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-regex和-iregex通过 regex (正则表达式)测试匹配的路径名.- 注意事项:两种实现都提供至少2种正则表达式方言供您选择(
-E激活对BSDfind中 extended 正则表达式的支持，而GNUfind允许从以下几种方言中进行选择:-regextype，但是在两种实现方式中，没有两种方言是完全相同的-请参见底部的血腥细节.
-inameand-ipath, which work like their standard-compliant counterparts (based on patterns), except that they match case-insensitively.-regexand-iregextests for matching pathnames by regex (regular expression).- Caveat: Both implementations offer at least 2 regex dialects to choose from (
-Eactivates support for extended regular expressions in BSDfind, and GNUfindallows selecting from several dialects with-regextype, but no two dialects are exactly the same across the two implementations - see bottom for the gory details.
使用固定宽度命名方案的文件夹名称后，模式将起作用:
With your folder names following a fixed-width naming scheme, a pattern would work:
pattern='[0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9]:[0-9][0-9]:[0-9][0-9]:[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'当然，如果您不希望误报，可以采取捷径:
Of course, you can take a shortcut if you don't expect false positives:
pattern='[0-9]*-[0-9]?:[0-9]?:[0-9]?:[0-9]*'请注意，与正则表达式不同，
*和?如何不是引用前一个表达式的重复符号(量词)，而是本身表示任何字符序列(*)或任何单个字符(?).Note how
*and?, unlike in a regex, are not duplication symbols (quantifiers) that refer to the preceding expression, but by themselves represent any sequence of characters (*) or any single character (?).如果我们将它们放在一起:
If we put it all together:
files=$(find "$path" -type d -name "$pattern")-
对变量引用进行双引号很重要，以保护其值免受不必要的shell扩展的影响，尤其是保留路径中的任何空格并防止shell过早地泛化 的值为
$pattern.It's important to double-quote the variable references to protect their values from unwanted shell expansions, notably to preserve any whitespace in the path and to prevent premature globbing by the shell of value
$pattern.请注意，我添加了
-type d来限制与目录(文件夹)的匹配，从而提高了性能.Note that I've added
-type dto limit matching to directories (folders), which improves performance.可选背景信息:
以下是 regex功能矩阵，从macOS 10.12.1上的GNU
findv4.6.0/BSDfind开始:Below is a regex feature matrix as of GNU
findv4.6.0 / BSDfindas found on macOS 10.12.1:-
GNU
find功能按-regextype选项支持的类型列出，默认值为emacs.
GNU
findfeatures are listed by the types supported by the-regextypeoption, withemacsbeing the default.
- 请注意，几种
posix-*命名的正则表达式类型是错误的名词，因为它们支持POSIX要求的功能 .
- Note that several
posix-*-named regex types are misnomers in that they support features beyond what POSIX mandates.
BSD
find功能由basic列出(使用NO regex选项，这意味着平台风格的BSD
findfeatures are listed bybasic(using NO regex option, which implies platform-flavored BREs) andextended(using option-E, which implies platform-flavored EREs).对于跨平台使用，请遵循 POSIX ERE( extended 正则表达式)，同时在 GNU
find中使用-regextype posix-extended并在 BSDfind中使用-E是安全的，但请注意，并非您可能期望的所有功能都受支持，尤其是\b，\</\>和字符类快捷方式(例如\d).For cross-platform use, sticking with POSIX EREs (extended regular expressions) while using
-regextype posix-extendedwith GNUfindand using-Ewith BSDfindis safe, but note that not all features you may expect will be supported, notably\b,\</\>and character class shortcuts such as\d.=================== GNU find =================== == REGEX FEATURE: \{\} TYPE: awk: - TYPE: egrep: - TYPE: ed: ✓ TYPE: emacs: - TYPE: gnu-awk: - TYPE: grep: ✓ TYPE: posix-awk: - TYPE: posix-basic: ✓ TYPE: posix-egrep: - TYPE: posix-extended: - TYPE: posix-minimal-basic: ✓ TYPE: sed: ✓ == REGEX FEATURE: {} TYPE: awk: - TYPE: egrep: ✓ TYPE: ed: - TYPE: emacs: - TYPE: gnu-awk: ✓ TYPE: grep: - TYPE: posix-awk: ✓ TYPE: posix-basic: - TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: - TYPE: sed: - == REGEX FEATURE: \+ TYPE: awk: - TYPE: egrep: - TYPE: ed: ✓ TYPE: emacs: - TYPE: gnu-awk: - TYPE: grep: ✓ TYPE: posix-awk: - TYPE: posix-basic: ✓ TYPE: posix-egrep: - TYPE: posix-extended: - TYPE: posix-minimal-basic: - TYPE: sed: ✓ == REGEX FEATURE: + TYPE: awk: ✓ TYPE: egrep: ✓ TYPE: ed: - TYPE: emacs: ✓ TYPE: gnu-awk: ✓ TYPE: grep: - TYPE: posix-awk: ✓ TYPE: posix-basic: - TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: - TYPE: sed: - == REGEX FEATURE: \b TYPE: awk: - TYPE: egrep: ✓ TYPE: ed: ✓ TYPE: emacs: ✓ TYPE: gnu-awk: ✓ TYPE: grep: ✓ TYPE: posix-awk: - TYPE: posix-basic: ✓ TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: ✓ TYPE: sed: ✓ == REGEX FEATURE: \< \> TYPE: awk: - TYPE: egrep: ✓ TYPE: ed: ✓ TYPE: emacs: ✓ TYPE: gnu-awk: ✓ TYPE: grep: ✓ TYPE: posix-awk: - TYPE: posix-basic: ✓ TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: ✓ TYPE: sed: ✓ == REGEX FEATURE: [:digit:] TYPE: awk: ✓ TYPE: egrep: ✓ TYPE: ed: ✓ TYPE: emacs: - TYPE: gnu-awk: ✓ TYPE: grep: ✓ TYPE: posix-awk: ✓ TYPE: posix-basic: ✓ TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: ✓ TYPE: sed: ✓ == REGEX FEATURE: \d TYPE: awk: - TYPE: egrep: - TYPE: ed: - TYPE: emacs: - TYPE: gnu-awk: - TYPE: grep: - TYPE: posix-awk: - TYPE: posix-basic: - TYPE: posix-egrep: - TYPE: posix-extended: - TYPE: posix-minimal-basic: - TYPE: sed: - == REGEX FEATURE: \s TYPE: awk: ✓ TYPE: egrep: ✓ TYPE: ed: - TYPE: emacs: ✓ TYPE: gnu-awk: ✓ TYPE: grep: - TYPE: posix-awk: ✓ TYPE: posix-basic: - TYPE: posix-egrep: ✓ TYPE: posix-extended: ✓ TYPE: posix-minimal-basic: - TYPE: sed: - =================== BSD find =================== == REGEX FEATURE: \{\} TYPE: basic: ✓ TYPE: extended: - == REGEX FEATURE: {} TYPE: basic: - TYPE: extended: ✓ == REGEX FEATURE: \+ TYPE: basic: - TYPE: extended: - == REGEX FEATURE: + TYPE: basic: - TYPE: extended: ✓ == REGEX FEATURE: \b TYPE: basic: - TYPE: extended: - == REGEX FEATURE: \< \> TYPE: basic: - TYPE: extended: - == REGEX FEATURE: [:digit:] TYPE: basic: ✓ TYPE: extended: ✓ == REGEX FEATURE: \d TYPE: basic: - TYPE: extended: - == REGEX FEATURE: \s TYPE: basic: - TYPE: extended: ✓这篇关于筛选名称为时间戳的文件夹-使用find实用工具进行模式匹配与正则表达式匹配的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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- Caveat: Both implementations offer at least 2 regex dialects to choose from (
- 注意事项:两种实现都提供至少2种正则表达式方言供您选择(
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