扣丁學堂Linux培訓簡述shell for循環、循環變量值付給其餘shell腳本的方法

本篇文章扣丁學堂Linux培訓小編就爲讀者們分享一下shell for循環、循環變量值付給其餘shell腳本的方法，對Linux開發技術感興趣的小夥伴就隨小編來了解一下吧，但願對你們有所幫助。

本文主要將在shell中如何編寫for循環，並將循環變量做爲下個shell腳本的參數。

shell for 循環：

!第一種寫法 相似C、Java

for ((i=1; i<=100; i ++))

do

echo $i

done

!第二種寫法 in應用

for i in {1..100}

do

echo $i

done

!第三種寫法 seq 使用

for i in seq 1 100

do

echo $i

done

將循環變量賦值到下一個腳本：

在運行shell腳本時候，有三種方式來調用外部的腳本，exec（exec script.sh）、source（source script.sh）、fork（./script.sh）

一、exec（exec /home/script.sh）：

使用exec來調用腳本，被執行的腳本會繼承當前shell的環境變量。但事實上exec產生了新的進程，他會把主shell的進程資源佔用並替換腳本內容，繼承了原主shell的PID號，即原主shell剩下的內容不會執行。

二、source（source /home/script.sh）

使用source或者「.」來調用外部腳本，不會產生新的進程，繼承當前shell環境變量，並且被調用的腳本運行結束後，它擁有的環境變量和聲明變量會被當前shell保留，相似將調用腳本的內容複製過來直接執行。執行完畢後原主shell繼續運行。

三、fork（/home/script.sh）

直接運行腳本，會以當前shell爲父進程，產生新的進程，而且繼承主腳本的環境變量和聲明變量。執行完畢後，主腳本不會保留其環境變量和聲明變量。

!main.sh主體

!/bin/sh

a=main

echo "a is $a"

echo "PID for parent before 2.sh:$$"

case $1 in

exec)

echo "using exec"

exec ./2.sh ;;

*)

echo "using sourcing"

source ./2.sh ;;

esac

echo "PID FOR parent after 2.sh :$$"

echo "now m"

！2.sh

!/bin/sh

echo "PID FOR 2.SH:$$"

echo "2.sh get a from main.sh is $a"

a=2.sh

export a

b=3.sh

echo "now 2.sh a is $a"

執行結果：

a is main

PID for parent before 2.sh:1162

using sourcing

PID FOR 2.SH:1162

2.sh get a from main.sh is main這裏寫代碼片

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1162

now m

經過for循環，循環變量做爲2.sh變量賦值並執行。

！main主函數

!/bin/sh

a=0

for ((i=1; i<=10; i ++))

do

a=$i

echo "a is $a"

echo "PID for parent before 2.sh:$$"

    echo "using sourcing"

    source ./2.sh

echo "PID FOR parent after 2.sh :$$"

echo "now a is $a"

done

輸出結果：

a is 1

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 1

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 2

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 2

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 3

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 3

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 4

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 4

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 5

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 5

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 6

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 6

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 7

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 7

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 8

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 8

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 9

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 9

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 10

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 10

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

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