Что делает команда 'grep'?
Я хотел бы узнать, как использовать его, чтобы я мог начать использовать терминал больше.
5 ответов
Имя:
grep, egrep, fgrep - print lines matching a pattern
РЕЗЮМЕ
grep [options] PATTERN [FILE...]
grep [options] [-e PATTERN | -f FILE] [FILE...]
ОПИСАНИЕ
Grep searches the named input FILEs (or standard input if no files are
named, or the file name - is given) for lines containing a match to the
given PATTERN. By default, grep prints the matching lines.
In addition, two variant programs egrep and fgrep are available. Egrep
is the same as grep -E. Fgrep is the same as grep -F.
ОПЦИИ
-A NUM, --after-context=NUM
Print NUM lines of trailing context after matching lines.
Places a line containing -- between contiguous groups of
matches.
-a, --text
Process a binary file as if it were text; this is equivalent to
the --binary-files=text option.
-B NUM, --before-context=NUM
Print NUM lines of leading context before matching lines.
Places a line containing -- between contiguous groups of
matches.
-C NUM, --context=NUM
Print NUM lines of output context. Places a line containing --
between contiguous groups of matches.
-b, --byte-offset
Print the byte offset within the input file before each line of
output.
--binary-files=TYPE
If the first few bytes of a file indicate that the file contains
binary data, assume that the file is of type TYPE. By default,
TYPE is binary, and grep normally outputs either a one-line mes-
sage saying that a binary file matches, or no message if there
is no match. If TYPE is without-match, grep assumes that a
binary file does not match; this is equivalent to the -I option.
If TYPE is text, grep processes a binary file as if it were
text; this is equivalent to the -a option. Warning: grep
--binary-files=text might output binary garbage, which can have
nasty side effects if the output is a terminal and if the termi-
nal driver interprets some of it as commands.
--colour[=WHEN], --color[=WHEN]
Surround the matching string with the marker find in GREP_COLOR
environment variable. WHEN may be 'never', 'always', or 'auto'
-c, --count
Suppress normal output; instead print a count of matching lines
for each input file. With the -v, --invert-match option (see
below), count non-matching lines.
-D ACTION, --devices=ACTION
If an input file is a device, FIFO or socket, use ACTION to pro-
cess it. By default, ACTION is read, which means that devices
are read just as if they were ordinary files. If ACTION is
skip, devices are silently skipped.
-d ACTION, --directories=ACTION
If an input file is a directory, use ACTION to process it. By
default, ACTION is read, which means that directories are read
just as if they were ordinary files. If ACTION is skip, direc-
tories are silently skipped. If ACTION is recurse, grep reads
all files under each directory, recursively; this is equivalent
to the -r option.
-E, --extended-regexp
Interpret PATTERN as an extended regular expression (see below).
-e PATTERN, --regexp=PATTERN
Use PATTERN as the pattern; useful to protect patterns beginning
with -.
-F, --fixed-strings
Interpret PATTERN as a list of fixed strings, separated by new-
lines, any of which is to be matched.
-P, --perl-regexp
Interpret PATTERN as a Perl regular expression.
-f FILE, --file=FILE
Obtain patterns from FILE, one per line. The empty file con-
tains zero patterns, and therefore matches nothing.
-G, --basic-regexp
Interpret PATTERN as a basic regular expression (see below).
This is the default.
-H, --with-filename
Print the filename for each match.
-h, --no-filename
Suppress the prefixing of filenames on output when multiple
files are searched.
--help Output a brief help message.
-I Process a binary file as if it did not contain matching data;
this is equivalent to the --binary-files=without-match option.
-i, --ignore-case
Ignore case distinctions in both the PATTERN and the input
files.
-L, --files-without-match
Suppress normal output; instead print the name of each input
file from which no output would normally have been printed. The
scanning will stop on the first match.
-l, --files-with-matches
Suppress normal output; instead print the name of each input
file from which output would normally have been printed. The
scanning will stop on the first match.
-m NUM, --max-count=NUM
Stop reading a file after NUM matching lines. If the input is
standard input from a regular file, and NUM matching lines are
output, grep ensures that the standard input is positioned to
just after the last matching line before exiting, regardless of
the presence of trailing context lines. This enables a calling
process to resume a search. When grep stops after NUM matching
lines, it outputs any trailing context lines. When the -c or
--count option is also used, grep does not output a count
greater than NUM. When the -v or --invert-match option is also
used, grep stops after outputting NUM non-matching lines.
--mmap If possible, use the mmap(2) system call to read input, instead
of the default read(2) system call. In some situations, --mmap
yields better performance. However, --mmap can cause undefined
behavior (including core dumps) if an input file shrinks while
grep is operating, or if an I/O error occurs.
-n, --line-number
Prefix each line of output with the line number within its input
file.
-o, --only-matching
Show only the part of a matching line that matches PATTERN.
--label=LABEL
Displays input actually coming from standard input as input com-
ing from file LABEL. This is especially useful for tools like
zgrep, e.g. gzip -cd foo.gz |grep -H --label=foo something
--line-buffered
Use line buffering, it can be a performance penality.
-q, --quiet, --silent
Quiet; do not write anything to standard output. Exit immedi-
ately with zero status if any match is found, even if an error
was detected. Also see the -s or --no-messages option.
-R, -r, --recursive
Read all files under each directory, recursively; this is equiv-
alent to the -d recurse option.
--include=PATTERN
Recurse in directories only searching file matching PATTERN.
--exclude=PATTERN
Recurse in directories skip file matching PATTERN.
-s, --no-messages
Suppress error messages about nonexistent or unreadable files.
Portability note: unlike GNU grep, traditional grep did not con-
form to POSIX.2, because traditional grep lacked a -q option and
its -s option behaved like GNU grep's -q option. Shell scripts
intended to be portable to traditional grep should avoid both -q
and -s and should redirect output to /dev/null instead.
-U, --binary
Treat the file(s) as binary. By default, under MS-DOS and MS-
Windows, grep guesses the file type by looking at the contents
of the first 32KB read from the file. If grep decides the file
is a text file, it strips the CR characters from the original
file contents (to make regular expressions with ^ and $ work
correctly). Specifying -U overrules this guesswork, causing all
files to be read and passed to the matching mechanism verbatim;
if the file is a text file with CR/LF pairs at the end of each
line, this will cause some regular expressions to fail. This
option has no effect on platforms other than MS-DOS and MS-Win-
dows.
-u, --unix-byte-offsets
Report Unix-style byte offsets. This switch causes grep to
report byte offsets as if the file were Unix-style text file,
i.e. with CR characters stripped off. This will produce results
identical to running grep on a Unix machine. This option has no
effect unless -b option is also used; it has no effect on
platforms other than MS-DOS and MS-Windows.
-V, --version
Print the version number of grep to standard error. This ver-
sion number should be included in all bug reports (see below).
-v, --invert-match
Invert the sense of matching, to select non-matching lines.
-w, --word-regexp
Select only those lines containing matches that form whole
words. The test is that the matching substring must either be
at the beginning of the line, or preceded by a non-word con-
stituent character. Similarly, it must be either at the end of
the line or followed by a non-word constituent character. Word-
constituent characters are letters, digits, and the underscore.
-x, --line-regexp
Select only those matches that exactly match the whole line.
-y Obsolete synonym for -i.
-Z, --null
Output a zero byte (the ASCII NUL character) instead of the
character that normally follows a file name. For example, grep
-lZ outputs a zero byte after each file name instead of the
usual newline. This option makes the output unambiguous, even
in the presence of file names containing unusual characters like
newlines. This option can be used with commands like find
-print0, perl -0, sort -z, and xargs -0 to process arbitrary
file names, even those that contain newline characters.
SOURCE:MANPAGE ДЛЯ GREP
Можно узнать о командах путем ввода
info <command>
man <command>
whatis <command>
apropos <command>
в терминале.
grep используется для поиска текста из файла или вывода другой команды. Он может вернуть строки, в которых он находит совпадение, или строки, в которых он не найден.
Вы отметили свой вопрос с grep тег. Но было лучше при чтении сначала информации о теге, относящейся к grep:
grepутилита командной строки, которая используется для поиска текста от стандартного входа или файла для определенных выражений, возвращая строки, где соответствия происходят.Общее использование для
grepдолжен расположиться и распечатать определенные строки от вывода программы или файлов журнала.Посмотрите эту страницу Ubuntu Documentation для получения дополнительной информации о том, как использовать
grep.
Кроме того, почти любая команда имеет страницу руководства, что можно считать ее. В Вашем случае используйте эту команду:
man grep
Еще больше можно получить информацию о grep использование одной из этих команд: info grep, grep -h, grep --help, whatis grep или apropos grep.
grep ищет содержимое файлов на основе регулярного выражения. Самый простой способ его использования - что-то вроде grep "word" file.txt, и в этом случае он будет просто возвращать каждую строку, где слово «word» появляется в файле file.txt (или ничего, если его там нет). Чтобы заставить его делать более сложные вещи, узнайте о регулярных выражениях. Вы можете найти множество учебников онлайн с помощью поиска. http://lmgtfy.com/?q=grep+tutorial
Лично я не рекомендую использовать терминал только ради использования терминала. Возможно, вам придется столкнуться с большими трудностями при изучении сложных инструментов, таких как grep, и обнаружить, что вы используете графические программы или сценарии, написанные на вашем любимом интерпретируемом языке. Большинство людей, которые рекомендуют изучать старомодные терминальные команды, сами являются старомодными хакерами.
Команда поиск GREP один или более входных файлов для строк, содержащих совпадение с заданным шаблоном. По умолчанию grep печатает совпадающие строки.
Grep выполняет поиск именованных входных ФАЙЛОВ (или стандартного ввода, если файлы не названы, или имя файла - задано) для строк, содержащих совпадение с заданным ШАБЛОНОМ. По умолчанию grep печатает совпадающие строки.
Кроме того, доступны две альтернативные программы egrep и fgrep. Egrep такой же, как grep -E. Fgrep - это то же самое, что и grep -F. Man Page
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