Английская Википедия:Glob (programming)
Шаблон:Short description
Шаблон:Lowercase
Шаблон:Use dmy dates
In computer programming, glob (Шаблон:IPAc-en) patterns specify sets of filenames with wildcard characters. For example, the Unix Bash shell command mv *.txt textfiles/
moves all files with names ending in .txt
from the current directory to the directory textfiles
. Here, *
is a wildcard and *.txt
is a glob pattern. The wildcard *
stands for "any string of any length including empty, but excluding the path separator characters (/
in unix and \
in windows)".
The other common wildcard is the question mark (?
), which stands for one character. For example, mv ?.txt shorttextfiles/
will move all files named with a single character followed by .txt
from the current directory to directory shorttextfiles
, while ??.txt
would match all files whose name consists of 2 characters followed by .txt
.
In addition to matching filenames, globs are also used widely for matching arbitrary strings (wildcard matching). In this capacity a common interface is fnmatch
.
Origin
glob
– the owner is dmr
, short for Dennis Ritchie.The glob command, short for global, originates in the earliest versions of Bell Labs' Unix.[1] The command interpreters of the early versions of Unix (1st through 6th Editions, 1969–1975) relied on a separate program to expand wildcard characters in unquoted arguments to a command: /etc/glob. That program performed the expansion and supplied the expanded list of file paths to the command for execution.
Glob was originally written in the B programming language. It was the first piece of mainline Unix software to be developed in a high-level programming language.[2] Later, this functionality was provided as a C library function, glob()
, used by programs such as the shell. It is usually defined based on a function named fnmatch()
, which tests for whether a string matches a given pattern - the program using this function can then iterate through a series of strings (usually filenames) to determine which ones match. Both functions are a part of POSIX: the functions defined in POSIX.1 since 2001, and the syntax defined in POSIX.2.[3][4] The idea of defining a separate match function started with wildmat (wildcard match), a simple library to match strings against Bourne Shell globs.
Traditionally, globs do not match hidden files in the form of Unix dotfiles; to match them the pattern must explicitly start with .
. For example, *
matches all visible files while .*
matches all hidden files.
Syntax
The most common wildcards are Шаблон:Code, Шаблон:Code, and Шаблон:Code.
Wildcard | Description | Example | Matches | Does not match |
---|---|---|---|---|
Шаблон:Code | matches any number of any characters including none | Шаблон:Code | Шаблон:Code, Шаблон:Code, or Шаблон:Code | Шаблон:Code, Шаблон:Code, or Шаблон:Code |
Шаблон:Code | Шаблон:Code, Шаблон:Code, or Шаблон:Code. | Шаблон:Code, or Шаблон:Code | ||
Шаблон:Code | matches any single character | Шаблон:Code | Шаблон:Code, Шаблон:Code, Шаблон:Code or Шаблон:Code | Шаблон:Code |
Шаблон:Code | matches one character given in the bracket | Шаблон:Code | Шаблон:Code or Шаблон:Code | Шаблон:Code, Шаблон:Code or Шаблон:Code |
Шаблон:Code | matches one character from the (locale-dependent) range given in the bracket | Шаблон:Code | Шаблон:Code, Шаблон:Code, Шаблон:Code up to Шаблон:Code | Шаблон:Code, Шаблон:Code or Шаблон:Code |
Normally, the path separator character (Шаблон:Code on Linux/Unix, MacOS, etc. or Шаблон:Code on Windows) will never be matched. Some shells, such as Bash have functionality allowing users to circumvent this.[5]
Unix-likeШаблон:Anchor
On Unix-like systems Шаблон:Code, Шаблон:Code is defined as above while Шаблон:Code has two additional meanings:[6][7]
Wildcard | Description | Example | Matches | Does not match |
---|---|---|---|---|
Шаблон:Code | matches one character that is not given in the bracket | Шаблон:Code | Шаблон:Code, Шаблон:Code, or Шаблон:Code | Шаблон:Code |
Шаблон:Code | matches one character that is not from the range given in the bracket | Шаблон:Code | Шаблон:Code, Шаблон:Code, Шаблон:Code up to Шаблон:Code and Шаблон:Code etc. | Шаблон:Code, Шаблон:Code, Шаблон:Code or Шаблон:Code |
The ranges are also allowed to include pre-defined character classes, equivalence classes for accented characters, and collation symbols for hard-to-type characters. They are defined to match up with the brackets in POSIX regular expressions.[6][7]
Unix globbing is handled by the shell per POSIX tradition. Globbing is provided on filenames at the command line and in shell scripts.[8] The POSIX-mandated case
statement in shells provides pattern-matching using glob patterns.
Some shells (such as the C shell and Bash) support additional syntax known as alternation or brace expansion. Because it is not part of the glob syntax, it is not provided in case
. It is only expanded on the command line before globbing.
The Bash shell also supports the following extensions:[9]
- Extended globbing (extglob): allows other pattern matching operators to be used to match multiple occurrences of a pattern enclosed in parentheses, essentially providing the missing kleene star and alternation for describing regular languages. It can be enabled by setting the Шаблон:Code shell option. This option came from ksh93.[10] The GNU fnmatch and glob has an identical extension.[3]
- globstar: allows
**
on its own as a name component to recursively match any number of layers of non-hidden directories.[10] Also supported by the JS libraries and Python's glob.
Windows and DOS
[[File:IBM PC DOS 1.0 screenshot.png|thumb|The [[dir (command)|Шаблон:Code]] command with a glob pattern in IBM PC DOS 1.0.]]
The original DOS was a clone of CP/M designed to work on Intel's 8088 and 8086 processors. Windows shells, following DOS, do not traditionally perform any glob expansion in arguments passed to external programs. Shells may use an expansion for their own builtin commands:
- Windows PowerShell has all the common syntax defined as stated above without any additions.[11]
- COMMAND.COM and cmd.exe have most of the common syntax with some limitations: There is no Шаблон:Code and for COMMAND.COM the Шаблон:Code may only appear at the end of the pattern. It can not appear in the middle of a pattern, except immediately preceding the filename extension separator dot.
Windows and DOS programs receive a long command-line string instead of argv-style parameters, and it is their responsibility to perform any splitting, quoting, or glob expansion. There is technically no fixed way of describing wildcards in programs since they are free to do what they wish. Two common glob expanders include:[12]
- The Microsoft C Runtime (msvcrt) command-line expander, which only supports Шаблон:Code and Шаблон:Code.[13] Both ReactOS (crt/misc/getargs.c) and Wine (msvcrt/data.c) contain a compatible open-source implementation of Шаблон:Code, the function operating under-the-hood, in their core CRT.
- The Cygwin and MSYS Шаблон:Code command-line expander, which uses the unix-style Шаблон:Code routine under-the-hood, after splitting the arguments.
Most other parts of Windows, including the Indexing Service, use the MS-DOS style of wildcards found in CMD. A relic of the 8.3 filename age, this syntax pays special attention to dots in the pattern and the text (filename). Internally this is done using three extra wildcard characters, Шаблон:Code. On the Windows API end, the Шаблон:Tt equivalent is Шаблон:Tt, and Шаблон:Tt corresponds to its underlying Шаблон:Tt.[14] (Another fnmatch analogue is Шаблон:Tt.) Both open-source msvcrt expanders use Шаблон:Tt, so 8.3 filename quirks will also apply in them.
SQL
The SQL Шаблон:Code operator has an equivalent to Шаблон:Code and Шаблон:Code but not Шаблон:Code.
Common wildcard | SQL wildcard | Description |
---|---|---|
Шаблон:Code | Шаблон:Code | matches any single character |
Шаблон:Code | Шаблон:Code | matches any number of any characters including none |
Standard SQL uses a glob-like syntax for simple string matching in its LIKE
operator, although the term "glob" is not generally used in the SQL community. The percent sign (Шаблон:Code) matches zero or more characters and the underscore (Шаблон:Code) matches exactly one.
Many implementations of SQL have extended the LIKE
operator to allow a richer pattern-matching language, incorporating character ranges (Шаблон:Code), their negation, and elements of regular expressions.[15]
Compared to regular expressions
Globs do not include syntax for the Kleene star which allows multiple repetitions of the preceding part of the expression; thus they are not considered regular expressions, which can describe the full set of regular languages over any given finite alphabet.[16]
Common wildcard | Equivalent regular expression |
---|---|
Шаблон:Code | Шаблон:Code |
Шаблон:Code | Шаблон:Code |
Globs attempt to match the entire string (for example, Шаблон:Code matches S.DOC and SA.DOC, but not POST.DOC or SURREY.DOCKS), whereas, depending on implementation details, regular expressions may match a substring.
Implementing as regular expressions
The original Mozilla proxy auto-config implementation, which provides a glob-matching function on strings, uses a replace-as-RegExp implementation as above. The bracket syntax happens to be covered by regex in such an example.
Python's fnmatch uses a more elaborate procedure to transform the pattern into a regular expression.[17]
Other implementations
Beyond their uses in shells, globs patterns also find use in a variety of programming languages, mainly to process human input. A glob-style interface for returning files or an fnmatch-style interface for matching strings are found in the following programming languages:
- C# has multiple libraries available through NuGet such as
Glob
.[18] orDotNet.Glob
.[19] - D has a
globMatch
function in thestd.path
module.[20] - JavaScript has a library called
minimatch
which is used internally by npm, andmicromatch
, a purportedly more optimized, accurate and safer globbing implementation used by Babel and yarn.[21][22] - Go has a
Glob
function in thefilepath
package.[23] - Java has a
Files
class containing methods that operate on glob patterns.[24] - Haskell has a
Glob
package with the main moduleSystem.FilePath.Glob
. The pattern syntax is based on a subset of Zsh's. It tries to optimize the given pattern and should be noticeably faster than a naïve character-by-character matcher.[25] - Perl has both a
glob
function (as discussed in Larry Wall's book Programming Perl) and a Glob extension which mimics the BSD glob routine.[26] Perl's angle brackets can be used to glob as well:<*.log>
. - PHP has a
glob
function.[27] - Python has a
glob
module in the standard library which performs wildcard pattern matching on filenames,[28] and anfnmatch
module with functions for matching strings or filtering lists based on these same wildcard patterns.[17] Guido van Rossum, author of the Python programming language, wrote and contributed aglob
routine to BSD Unix in 1986.[29] There were previous implementations ofglob
, e.g., in the ex and ftp programs in previous releases of BSD. - Ruby has a
glob
method for theDir
class which performs wildcard pattern matching on filenames.[30] Several libraries such as Rant and Rake provide aFileList
class which has a glob method or use the methodFileList.[]
identically. - Rust has multiple libraries that can match glob patterns.[31]
- SQLite has a
GLOB
function. - Tcl contains a globbing facility.[32]
See also
References
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- ↑ 3,0 3,1 Шаблон:Man
- ↑ Шаблон:Man
- ↑ https://www.gnu.org/software/bash/manual/bash.html#Pattern-Matching Bash Reference Manual
- ↑ 6,0 6,1 Ошибка цитирования Неверный тег
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; для сносокposixglob
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; для сносокlinuxglob7
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокABSGlob
не указан текст - ↑ Шаблон:Cite web
- ↑ 10,0 10,1 Ошибка цитирования Неверный тег
<ref>
; для сносокbashpat
не указан текст - ↑ Ошибка цитирования Неверный тег
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; для сносокpwshcmdlet
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокwinWildcard
не указан текст - ↑ Шаблон:Cite web
- ↑ Wildcards in Windows. MSDN Devblog.
- ↑ Ошибка цитирования Неверный тег
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не указан текст - ↑ Шаблон:Cite book
- ↑ 17,0 17,1 Шаблон:Cite web
- ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокdotnet-glob
не указан текст - ↑ Ошибка цитирования Неверный тег
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; для сносокdotnet.glob
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<ref>
; для сносокdlang
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<ref>
; для сносокminimatch
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокmicromatch
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокgolang
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокjava
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокhs
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокpl
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокphp
не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокpyglob
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<ref>
; для сносокisc-glob
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<ref>
; для сносокrbdir
не указан текст - ↑ Шаблон:Cite web
- ↑ Ошибка цитирования Неверный тег
<ref>
; для сносокtcl
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