Basic Pipe Command

refer:

取值

Head

取出前面幾行

Option	Action
-n num	取出前面n行

Tail

取出後面幾行

Option	Action
-n num	取出後面n行
-f	Keep output appended data as the file grows; Press 'Ctrl+c' to exit

Grep

Option	Action
-i	忽略大小寫
-n	顯示行數
-v abc	過濾 abc
-A x	後面x列
-B y	前面y列

Cut

usage	notes
cut -d '分隔字元' -f fields	field從 1 開始計數
cut -c A-B	取每一行第Ａ到第Ｂ個字元

$ cat >> phone_book << EOF
> tsungyi 03-1234567
> brandon 03-7654321
> batman 05-1234321
> EOF

$ cat phone_book | cut -d ' ' -f 1
tsungyi
brandon
batman

$ cat phone_book | cut -c 1-5
tsung
brand
batma

AWK

refer: http://blog.xuite.net/mb1016.flying/linux/28111008-linux+shell+awk+語法

進階版的cut

基本用法：

預設的『欄位的分隔符號為 "空白鍵" 或 "[tab]鍵" 』！
-F "新分隔符號"
每一行的每個欄位都是有變數名稱的，那就是 $1, $2... 等變數名稱。
$0 代表『一整列資料』的意思

$ cat >> phone_book << EOF
> tsungyi 03-1234567
> brandon 03-7654321
> batman 05-1234321
> EOF

$ awk '{print $2}' ./phone_book 
03-1234567
03-7654321
05-1234321

$ awk -F '-' '{print $2}' ./phone_book 
1234567
7654321
1234321

加條件進階用法

awk ' (條件) {print}'
邏輯運算：> , < , >= , <= , == , !=
使用布爾運算符 "||"（邏輯與）和 "&&"（邏輯或）
($1 ~ /正規表示式/) || ($1 !~ /正規表示式/)

$ awk '($1 == "brandon"){print $2}' ./phone_book 
03-7654321

$ awk '($1 == "brandon")||($1 == "batman"){print $2}' ./phone_book 
03-7654321
05-1234321

$ awk '($2 ~ /03-[0-9]*/) {print $2}' ./phone_book 
03-1234567
03-7654321

$ awk '($2 !~ /03-[0-9]*/) {print $2}' ./phone_book 
05-1234321

記數

WC

通常跟 sort 及 uniq 一起用

$ wc [-lwm]

選項與參數：

-l ：僅列出行；
-w ：僅列出多少字(英文單字)；
-m ：多少字元；

$ cat phone_book | wc
       3       6      56
$ cat phone_book | wc -l
       3
$ cat phone_book | wc -w
       6
$ cat phone_book | wc -m
      56

sort

refer:

http://www.cyberciti.biz/faq/unix-linux-shell-script-sorting-ip-addresses/

options	notes
-t ＜separator＞	Set field separator
-k BEGIN[,END]	Sort data / fields using the given BEGIN column number to END column number.
-n	Makes the program sort according to numerical value
-r	reverse sort

sort ip address:

$ cat >> ips <<EOF 
10.0.0.4
10.0.1.5
10.0.0.3
10.0.1.11
10.0.1.12
10.0.0.11
10.0.0.12
EOF


$ sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n ips
10.0.0.3
10.0.0.4
10.0.0.11
10.0.0.12
10.0.1.5
10.0.1.11
10.0.1.12

$ sort -t . -k 1,1nr -k 2,2nr -k 3,3nr -k 4,4nr ips
10.0.1.12
10.0.1.11
10.0.1.5
10.0.0.12
10.0.0.11
10.0.0.4
10.0.0.3

uniq

report or filter out consecutive repeated lines in a file

通常跟sort 並用

-c : with the count of the number of times the line occurred in the input.
-d : Only output lines that are repeated in the input.
-u : Only output lines that are not repeated in the input.
-i : Case insensitive comparison of lines.

$ cat > phone_book << EOF
> tsungyi 03-1234567
> brandon 03-7654321
> batman 05-1234321
> brandon 03-7654321
> tsungyi 03-1234567
> EOF


$ cat phone_book | sort
batman 05-1234321
brandon 03-7654321
brandon 03-7654321
tsungyi 03-1234567
tsungyi 03-1234567

$ cat phone_book | sort | uniq
batman 05-1234321
brandon 03-7654321
tsungyi 03-1234567

$ cat phone_book | sort | uniq -c
   1 batman 05-1234321
   2 brandon 03-7654321
   2 tsungyi 03-1234567

$ cat phone_book | sort | uniq -d
brandon 03-7654321
tsungyi 03-1234567

$ cat phone_book | sort | uniq -u
batman 05-1234321

重導向

tee [-ai] [file]

tee 會同時將資料流分送到檔案去與螢幕 (screen)；而輸出到螢幕的，其實就是 stdout ，可以讓下個指令繼續處理喔！

optioon	notes
-a	Append the output to the files rather than overwriting them.
-i	Ignore the SIGINT signal.


$ cat phone_book | tee -a new_book | grep brandon
brandon 03-7654321

$ cat new_book 
tsungyi 03-1234567
brandon 03-7654321
batman 05-1234321

Pipe commands