1.指令英文解釋
| cat | Concatenate files |
| sort | Sort lines of text |
| uniq | Report or omit repeated lines |
| grep | Print lines matching a pattern |
| wc | Print newline, word, and byte counts for each file |
| head | Output the first part of a file |
| tail | Output the last part of a file |
| tee | Read from standard input and write to standard output and files |
2.指令詳解
| > | 將標準輸出重定向到除屏幕以外的另一個文件。 | A > B |
| >> | 重定向結果追加到文件內容後面 | A >> B |
| cat | 連接文件 | cat [file] |
| | |
管道線,用來作爲過濾器 |
A | B |
|
uniq |
報道或忽略重複行 |
A | B | uniq |
|
wc |
打印行數、字數和字節數 |
wc A |
|
grep |
打印匹配行 |
A | grep B |
|
head / tail |
打印文件開頭部分/結尾部分 |
head -n 5 B |
|
tee |
從 Stdin 讀取數據，並同時輸出到 Stdout 和文件 |
A | tee B |
3.指令常用技巧
> hello.txt 清空文件內容 A 0/1/2> B 其中2代表將錯誤信息輸入到B
A > B 2>&1 等價於 A > B 2 > B 等價於 A &> B 將A的信息以及錯誤信息都輸入到B
cat（用於連接多個文件形成一個完整的文件或從標準輸入讀入數據 比如 cat movie.mpeg.0* > movie.mpeg or 直接 cat）
注意：ctrl + d 等價於 EOF , 表示在操作系統中表示資料源無更多的資料可讀取，用來結束讀取輸入。
A | -d uniq 可以看到重複的是哪些
wc -l A 只能看見A的line行數
head -f B 可以實時監控文件是否發生改變
4.命令實例
[me@linuxbox ~]$ ls -l /usr/bin > ls-output.txt
[me@linuxbox ~]$ ls -l ls-output.txt
-rw-rw-r-- 1 me me 167878 2008-02-01 15:07 ls-output.txt
[me@linuxbox ~]$ less ls-output.txt
[me@linuxbox ~]$ ls -l /bin/usr > ls-output.txt
ls: cannot access /bin/usr: No such file or directory
me@linuxbox ~]$ ls -l ls-output.txt
-rw-rw-r-- 1 me me 0 2008-02-01 15:08 ls-output.txt
[me@linuxbox ~]$ > ls-output.txt
[me@linuxbox ~]$ ls -l /usr/bin >> ls-output.txt
[me@linuxbox ~]$ ls -l /usr/bin >> ls-output.txt
[me@linuxbox ~]$ ls -l /usr/bin >> ls-output.txt
[me@linuxbox ~]$ ls -l /usr/bin >> ls-output.txt
[me@linuxbox ~]$ ls -l ls-output.txt
-rw-rw-r-- 1 me me 503634 2008-02-01 15:45 ls-output.txt
[me@linuxbox ~]$ ls -l /bin/usr 2> ls-error.txt
[me@linuxbox ~]$ ls -l /bin/usr > ls-output.txt 2>&1
[me@linuxbox ~]$ ls -l /bin/usr &> ls-output.txt
[me@linuxbox ~]$ ls -l /bin/usr 2> /dev/null
[me@linuxbox ~]$ cat ls-output.txt
[me@linuxbox ~]$ cat movie.mpeg.0* > movie.mpeg
[me@linuxbox ~]$ cat
[me@linuxbox ~]$ cat
The quick brown fox jumped over the lazy dog.
[me@linuxbox ~]$ cat
The quick brown fox jumped over the lazy dog.
The quick brown fox jumped over the lazy dog.
[me@linuxbox ~]$ cat > lazy_dog.txt
The quick brown fox jumped over the lazy dog.
[me@linuxbox ~]$ cat lazy_dog.txt
The quick brown fox jumped over the lazy dog.
[me@linuxbox ~]$ cat < lazy_dog.txt
The quick brown fox jumped over the lazy dog.
[me@linuxbox ~]$ ls -l /usr/bin | less
[me@linuxbox ~]$ ls /bin /usr/bin | sort | less
[me@linuxbox ~]$ ls /bin /usr/bin | sort | uniq | less
[me@linuxbox ~]$ ls /bin /usr/bin | sort | uniq -d | less
[me@linuxbox ~]$ wc ls-output.txt
7902 64566 503634 ls-output.txt
[me@linuxbox ~]$ ls /bin /usr/bin | sort | uniq | wc -l
2728
[me@linuxbox ~]$ ls /bin /usr/bin | sort | uniq | grep zip
bunzip2
bzip2
gunzip
...
[me@linuxbox ~]$ head -n 5 ls-output.txt
total 343496
...
[me@linuxbox ~]$ tail -n 5 ls-output.txt
...
[me@linuxbox ~]$ ls /usr/bin | tail -n 5
znew
...
[me@linuxbox ~]$ tail -f /var/log/messages
Feb 8 13:40:05 twin4 dhclient: DHCPACK from 192.168.1.1
....
[me@linuxbox ~]$ ls /usr/bin | tee ls.txt | grep zip
bunzip2
bzip2
....
