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本文主要将在shell中如何編寫for循環，并将循環變量作為下個shell腳本的參數。
shell for 循環：
#!第一種寫法 類似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 複制
将循環變量指派到下一個腳本：
在運作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）
1、exec（exec /home/script.sh）：
使用exec來調用腳本，被執行的腳本會繼承目前shell的環境變量。但事實上exec産生了新的程序，他會把主shell的程序資源占用并替換腳本内容，繼承了原主shell的PID号，即原主shell剩下的内容不會執行。
2、source（source /home/script.sh）
使用source或者“.”來調用外部腳本，不會産生新的程序，繼承目前shell環境變量，而且被調用的腳本運作結束後，它擁有的環境變量和聲明變量會被目前shell保留，類似将調用腳本的内容複制過來直接執行。執行完畢後原主shell繼續運作。
3、fork（/home/script.sh）
直接運作腳本，會以目前shell為父程序，産生新的程序，并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" 複制
#！2.sh
#!/bin/sh
echo "PID FOR 2.SH:$$"
echo "2.sh get a from main.sh is $a"
a=2.sh
export a
b=3.sh
echo "now 2.sh a is $a" 複制
執行結果：
a is main
PID for parent before 2.sh:1162
using sourcing
PID FOR 2.SH:1162
2.sh get a from main.sh is main`這裡寫代碼片`
now 2.sh a is 2.sh
PID FOR parent after 2.sh :1162
now m 複制
通過for循環，循環變量作為2.sh變量指派并執行。
#！main主函數
#!/bin/sh
a=0
for ((i=1; i<=10; i ++))
do
a=$i
echo "a is $a"
echo "PID for parent before 2.sh:$$"
echo "using sourcing"
source ./2.sh
echo "PID FOR parent after 2.sh :$$"
echo "now a is $a"
done 複制
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 複制
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釋出者：全棧程式員棧長，轉載請注明出處：https://javaforall.cn/163974.html原文連結：https://javaforall.cn