每天一个Linux命令（34）grep命令

      grep（global search regular expression(RE) and print out the line，全面搜索正则表达式并把行打印出来）是一种强大的文本搜索工具，它能使用正则表达式搜索文本，并把匹配的行打印出来。

      (1)用法:

      用法:  grep [选项]... PATTERN [FILE]...

      (2)功能:

      功能:  在每个 FILE 或是标准输入中查找 PATTERN。

      (3)选项参数:

      1) -V, --version 　　　　　　　　　　显示版本号

      2) -i　　　　　　　　　　　　　　　　在匹配过程中忽略大小写

      3) -v, --invert-match 　　　　　　　 显示不匹配的行 

      4) -f　　　　　　　　　　　　　　　　指定文件中存的每行字符串作为匹配字符串

      5) -c　　　　　　　　　　　　　　　　统计每个文件中包含指定字符串的行数

      6) --color=auto　　　　　　　　　　  标记匹配颜色

      7) -E 　　　　　　　　　　　　　　　  将范本样式为延伸的普通表示法来使用，意味着使用能使用扩展正则表达式

      8) -q　　　　　　　　　　　　　　　　 grep静默输出，常用来测试。

      (4)实例:

      1)[root@localhost grepDir]# grep "MenAngel" t1.txt t2.txt t3.txt　　　　　　　　　　在特定的文本集中查找特定字符串

[root@localhost grepDir]# cat >t1.txt
I'm MenAngel!
Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!
^Z
[3]+  已停止               cat > t1.txt
[root@localhost grepDir]# cat >t2.txt
Every one fights for a better future,but I fight for freedom!                     
^Z
[4]+  已停止               cat > t2.txt
[root@localhost grepDir]# cat >t3.txt <<EOF
> There is no one hoping that you will succeed when you are been looking down upon,but if you succeeded,they will look down upon themselves!
> When you get an important thing,you will find that it is not so precious as you like,but when you lose it after that,it will become so precious as you liked.
> EOF
[root@localhost grepDir]# grep "MenAngel" t1.txt t2.txt t3.txt
t1.txt:I'm MenAngel!

      2)[root@localhost grepDir]# grep -v "MenAngel" t1.txt t2.txt t3.txt　　　　　　　　输出指定字符串所在行之外的所有文件的行内容

[root@localhost grepDir]# grep -v "MenAngel" t1.txt t2.txt t3.txt
t1.txt:Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!
t2.txt:Every one fights for a better future,but I fight for freedom!
t3.txt:There is no one hoping that you will succeed when you are been looking down upon,but if you succeeded,they will look down upon themselves!
t3.txt:When you get an important thing,you will find that it is not so precious as you like,but when you lose it after that,it will become so precious as you liked.

      3)[root@localhost grepDir]# grep "fight" t1.txt t2.txt t3.txt --color=auto　　　　　 将查找的字符串用特定的颜色标记出来

[root@localhost grepDir]# grep "fight" t1.txt t2.txt t3.txt --color=auto
t2.txt:Every one fights for a better future,but I fight for freedom!

      4)[root@localhost grepDir]# grep -c "that" t1.txt t2.txt t3.txt　　　　　　　　　　　 统计每个文件中包含指定字符串的行数

[root@localhost grepDir]# grep -c "that" t1.txt t2.txt t3.txt
t1.txt:1
t2.txt:0
t3.txt:2

      5)[root@localhost grepDir]# grep -n "that" t1.txt t2.txt t3.txt　　　　　　　　　　   默认情况，输出包含特定字符串所在的行

[root@localhost grepDir]# grep -n "that" t1.txt t2.txt t3.txt
t1.txt:2:Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!
t3.txt:1:There is no one hoping that you will succeed when you are been looking down upon,but if you succeeded,they will look down upon themselves!
t3.txt:2:When you get an important thing,you will find that it is not so precious as you like,but when you lose it after that,it will become so precious as you liked.
[root@localhost grepDir]# grep "that" t1.txt t2.txt t3.txt
t1.txt:Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!
t3.txt:There is no one hoping that you will succeed when you are been looking down upon,but if you succeeded,they will look down upon themselves!
t3.txt:When you get an important thing,you will find that it is not so precious as you like,but when you lose it after that,it will become so precious as you liked.

      6)[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep "MenAngel"　　　　　　　　配合cat命令查看文件中指定字符串所在行的内容

[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep "MenAngel"
I'm MenAngel!
[root@localhost grepDir]# grep "MenAngel" t1.txt t2.txt t3.txt
t1.txt:I'm MenAngel!

      7)[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep ^I　　　　　　　　　　　　　查找以指定字符串开头的文本行并输出

[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep ^I
I'm MenAngel!
[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep ^M  //没有以M开头的
[root@localhost grepDir]# 

      8)[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep ^[^I]　　　　　　　　　　　 经不以指定字符串开头的文本所在行的内容输出

[root@localhost grepDir]# cat t1.txt t2.txt t3.txt|grep ^[^I]
Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!
Every one fights for a better future,but I fight for freedom!
There is no one hoping that you will succeed when you are been looking down upon,but if you succeeded,they will look down upon themselves!
When you get an important thing,you will find that it is not so precious as you like,but when you lose it after that,it will become so precious as you liked.
[root@localhost grepDir]# 

      9)[root@localhost grepDir]# seq 10|grep "5" -C|-A|-B 3　　　　　　　　　　　　　    显示特定行的前面或后面的内容　　　　　

[root@localhost grepDir]# seq 10|grep "5" -C 3
2
3
4
5
6
7
8
[root@localhost grepDir]# seq 10|grep "5" -A 3
5
6
7
8
[root@localhost grepDir]# seq 10|grep "5" -B 3
2
3
4
5

      10)[root@localhost grepDir]# grep -C 3 "MenAngel" t1.txt t2.txt t3.txt　　　　　　无论用不用通道，参数都是可用的

[root@localhost grepDir]# grep -C 3 "MenAngel" t1.txt t2.txt t3.txt
t1.txt:I'm MenAngel!
t1.txt-Although I'm still a poor student right now,I believe that someday I will be one of the successful man in the world!

      11)[root@localhost grepDir]# echo -e "a b c a b c" | grep a -A 1　　　　　　如果匹配结果有多个，会用“--”作为各匹配结果之间的分隔符

[root@localhost grepDir]# echo -e "a
b
c
a
b
c" | grep a -A 1
a
b
--
a
b
[root@localhost grepDir]# 
[root@localhost grepDir]# echo -e "a
b
c
d
a
b
c
d" | grep a -A 1
a
b
--
a
b
[root@localhost grepDir]# echo -e "a
b
c
d
a
b
c
d" | grep a -A 2
a
b
c
--
a
b
c

      12)[root@localhost grepDir]# echo this is a text line | grep -e "is" -e "line" -o　　　　　　　　　 制动多个匹配样式

[root@localhost grepDir]# echo this is a text line | grep -e "is" -e "line" -o   //grep这里处理的是前面的echo输出的内容
is
is
line

      13)[root@localhost grepDir]# echo MenAngel is sunjimeng|grep -f patfile　　　　　　　　　　　 指定在文件中每行存的多个字符串

[root@localhost grepDir]# cat >patfile <<EOF
> MenAngel
> sunjimeng
> EOF
[root@localhost grepDir]# echo MenAngel is sunjimeng|grep -f patfile
MenAngel is sunjimeng
[root@localhost grepDir]# 

      14)[root@localhost grepDir]# grep --help

[root@localhost grepDir]# grep --help
用法: grep [选项]... PATTERN [FILE]...
在每个 FILE 或是标准输入中查找 PATTERN。
默认的 PATTERN 是一个基本正则表达式(缩写为 BRE)。
例如: grep -i 'hello world' menu.h main.c

正则表达式选择与解释:
  -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

Miscellaneous:
  -s, --no-messages         suppress error messages
  -v, --invert-match        select non-matching lines
  -V, --version             display version information and exit
      --help                display this help text and exit

输出控制:
  -m, --max-count=NUM       NUM 次匹配后停止
  -b, --byte-offset         输出的同时打印字节偏移
  -n, --line-number         输出的同时打印行号
      --line-buffered       每行输出清空
  -H, --with-filename       为每一匹配项打印文件名
  -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       show only the part of a line matching PATTERN
  -q, --quiet, --silent     suppress all normal output
      --binary-files=TYPE   assume that binary files are TYPE;
                            TYPE is 'binary', 'text', or 'without-match'
  -a, --text                equivalent to --binary-files=text
  -I                        equivalent to --binary-files=without-match
  -d, --directories=ACTION  how to handle directories;
                            ACTION is 'read', 'recurse', or 'skip'
  -D, --devices=ACTION      how to handle devices, FIFOs and sockets;
                            ACTION is 'read' or 'skip'
  -r, --recursive           like --directories=recurse
  -R, --dereference-recursive
                            likewise, but follow all symlinks
      --include=FILE_PATTERN
                            search only files that match FILE_PATTERN
      --exclude=FILE_PATTERN
                            skip files and directories matching FILE_PATTERN
      --exclude-from=FILE   skip files matching any file pattern from FILE
      --exclude-dir=PATTERN directories that match PATTERN will be skipped.
  -L, --files-without-match print only names of FILEs containing no match
  -l, --files-with-matches  print only names of FILEs containing matches
  -c, --count               print only a count of matching lines per FILE
  -T, --initial-tab         make tabs line up (if needed)
  -Z, --null                print 0 byte after FILE name

文件控制:
  -B, --before-context=NUM  打印以文本起始的NUM 行
  -A, --after-context=NUM   打印以文本结尾的NUM 行
  -C, --context=NUM         打印输出文本NUM 行
  -NUM                      same as --context=NUM
      --group-separator=SEP use SEP as a group separator
      --no-group-separator  use empty string as a group separator
      --color[=WHEN],
      --colour[=WHEN]       use markers to highlight the matching strings;
                            WHEN is 'always', 'never', or 'auto'
  -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)

‘egrep’即‘grep -E’。‘fgrep’即‘grep -F’。
直接使用‘egrep’或是‘fgrep’均已不可行了。
若FILE 为 -，将读取标准输入。不带FILE，读取当前目录，除非命令行中指定了-r 选项。
如果少于两个FILE 参数，就要默认使用-h 参数。
如果有任意行被匹配，那退出状态为 0，否则为 1；
如果有错误产生，且未指定 -q 参数，那退出状态为 2。

请将错误报告给: bug-grep@gnu.org
GNU Grep 主页: <http://www.gnu.org/software/grep/>
GNU 软件的通用帮助: <http://www.gnu.org/gethelp/>

       grep的用法远远不止这么多，以后如果见得多了，用的多了，再更新！