grep 命令
grep 命令用于查找文件里符合条件的文本。
语法
grep [选项]... PATTERN [FILE]...
- PATTERN：要搜索的模式（正则表达式或简单字符串）。
- FILE：要搜索的文件名。如果不提供文件名，则默认从标准输入读取数据并进行搜索,也可以使用通配符表示一类文件
选项：
PATTERN正则表达式选项:
-E, --extended-regexp PATTERN 是一个可扩展的正则表达式(缩写为 ERE)
-F, --fixed-strings PATTERN 是一组由断行符分隔的定长字符串。
-G, --basic-regexp PATTERN 是一个基本正则表达式(缩写为 BRE)
-P, --perl-regexp PATTERN 是一个 Perl 正则表达式
-e, --regexp=PATTERN 用 PATTERN 来进行匹配操作
-f, --file=FILE 从 FILE 中取得 PATTERN
-i, --ignore-case 忽略大小写
-w, --word-regexp 强制 PATTERN 仅完全匹配字词
-x, --line-regexp 强制 PATTERN 仅完全匹配一行
-z, --null-data 一个 0 字节的数据行，但不是空行
输出控制选项:
-m, --max-count=NUM 最多只匹配NUM次后停止
-n, --line-number 输出的同时打印行号
--line-buffered 每行输出清空
-b, --byte-offset 输出的同时打印字节偏移
-H, --with-filename 在每个匹配项前输出文件名
-h, --no-filename 输出时不显示文件名前缀
--label=LABEL 将LABEL 作为标准输入文件名前缀
-o, --only-matching 只输出匹配部分,不输出匹配行其他内容
-q, --quiet, --silent 只查找不输出匹配内容
--binary-files=TYPE assume that binary files are TYPE;
TYPE is 'binary', 'text', or 'without-match'
-a, --text 不要忽略二进制文件 --binary-files=text
-I equivalent to --binary-files=without-match
-d, --directories=ACTION 如何处理目录,ACTION可以是'read', 'recurse', or 'skip'
-r, --recursive 递归查找目录,同--directories=recurse
-R, --dereference-recursive
likewise, but follow all symlinks
--include=FILE_PATTERN
只搜索FILE_PATTERN匹配的文件
--exclude=FILE_PATTERN
排除FILE_PATTERN匹配的文件
--exclude-from=FILE 排除文件
--exclude-dir=PATTERN directories that match PATTERN will be skipped.
-L, --files-without-match 只打印没有匹配到的文件名
-l, --files-with-matches 只打印有匹配的文件名
-c, --count 只打印每个文件匹配到的次数
-T, --initial-tab make tabs line up (if needed)
-Z, --null print 0 byte after FILE nam
文件控制选项:
-B, --before-context=NUM 打印匹配到文件上下文的前NUM 行
-A, --after-context=NUM 打印匹配到文件上下文的后NUM 行
-C, --context=NUM 打印匹配到文件上下文的前后NUM 行
-NUM 同 -C
-U, --binary do not strip CR characters at EOL (MSDOS/Windows)
-u, --unix-byte-offsets report offsets as if CRs were not there
(MSDOS/Windows)
实例
1、在当前目录中的日志文件(.log文件)查找含'Exception'的内容。此时，可以使用如下命令：
grep 'Exception' *.log
结果如下所示：
log2023-02-04_0.log:org.jflame.toolkit.cache.RedisAccessException: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log2023-02-04_0.log:Caused by: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log2023-02-04_0.log:Caused by: redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log2023-02-04_0.log:Caused by: java.util.NoSuchElementException: Unable to validate object
log2023-02-04_0.log:org.jflame.toolkit.cache.RedisAccessException: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log.log:org.jflame.toolkit.cache.RedisAccessException: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log.log:Caused by: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log.log:Caused by: redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
log.log:Caused by: java.util.NoSuchElementException: Unable to validate object
2、以递归的方式查找符合条件的文件。例如，查找指定目录/etc/acpi 及其子目录（如果存在子目录的话）下所有文件中包含字符串"update"的文件，并打印出该字符串所在行的内容，使用的命令为：
grep -r update /etc/acpi
输出结果如下：
$ grep -r update /etc/acpi #以递归的方式查找“etc/acpi”
#下包含“update”的文件
/etc/acpi/ac.d/85-anacron.sh:# (Things like the slocate updatedb cause a lot of IO.)
Rather than
/etc/acpi/resume.d/85-anacron.sh:# (Things like the slocate updatedb cause a lot of
IO.) Rather than
/etc/acpi/events/thinkpad-cmos:action=/usr/sbin/thinkpad-keys--update
3、反向查找。前面各个例子是查找并打印出符合条件的行，通过"-v"参数可以打印出不符合条件行的内容。
查找文件名中包含 test 的文件中不包含 test 的行，此时，使用的命令为：
grep -v test *test*
结果如下所示：
$ grep-v test* #查找文件名中包含test 的文件中不包含test 的行
testfile1:helLinux!
testfile1:Linis a free Unix-type operating system.
testfile1:Lin
testfile_1:HELLO LINUX!
testfile_1:LINUX IS A FREE UNIX-TYPE OPTERATING SYSTEM.
testfile_1:THIS IS A LINUX TESTFILE!
testfile_2:HELLO LINUX!
testfile_2:is a free unix-type opterating system.
4、log.log文件中查找含'Exception'的内容,并打印出上下文的前10行
$ grep -10 'Exception' log.log
2023-02-06 09:47:54,978 ERROR[pool-4-thread-1] o.s.s.s.TaskUtils$LoggingErrorHandler - Unexpected error occurred in scheduled task.
org.jflame.toolkit.cache.RedisAccessException: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
at org.jflame.toolkit.cache.SpringCacheClientImpl.setIfAbsent(SpringCacheClientImpl.java:126)
at org.jflame.toolkit.lock.RedisLock.setNX(RedisLock.java:125)
at org.jflame.toolkit.lock.RedisLock.lock(RedisLock.java:73)
at com.ghgcn.support.job.AbstractJobWithDistribtedLock.execute(AbstractJobWithDistribtedLock.java:41)
at sun.reflect.GeneratedMethodAccessor198.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:204)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:348)
at org.springframework.data.redis.core.RedisConnectionUtils.doGetConnection(RedisConnectionUtils.java:129)
at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:92)
at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:79)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:194)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:169)