2019-05-09 11:06:07 3696瀏覽
本篇文章扣丁學(xué)堂Linux培訓(xùn)小編就為讀者們分享一下shell for循環(huán)、循環(huán)變量值付給其他shell腳本的方法，對Linux開發(fā)技術(shù)感興趣的小伙伴就隨小編來了解一下吧，希望對大家有所幫助。
本文主要將在shell中如何編寫for循環(huán)，并將循環(huán)變量作為下個shell腳本的參數(shù)。
shell for 循環(huán)：
#!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(yīng)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(huán)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(diào)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(diào)用腳本，被執(zhí)行的腳本會繼承當(dāng)前shell的環(huán)境變量。但事實上exec產(chǎn)生了新的進程，他會把主shell的進程資源占用并替換腳本內(nèi)容，繼承了原主shell的PID號，即原主shell剩下的內(nèi)容不會執(zhí)行。
2、source（source /home/script.sh）
使用source或者“.”來調(diào)用外部腳本，不會產(chǎn)生新的進程，繼承當(dāng)前shell環(huán)境變量，而且被調(diào)用的腳本運行結(jié)束后，它擁有的環(huán)境變量和聲明變量會被當(dāng)前shell保留，類似將調(diào)用腳本的內(nèi)容復(fù)制過來直接執(zhí)行。執(zhí)行完畢后原主shell繼續(xù)運行。
3、fork（/home/script.sh）
直接運行腳本，會以當(dāng)前shell為父進程，產(chǎn)生新的進程，并且繼承主腳本的環(huán)境變量和聲明變量。執(zhí)行完畢后，主腳本不會保留其環(huán)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:$$" echo "2.sh get a from main.sh is $a" a=2.sh export a b=3.sh echo "now 2.sh a is $a"
執(zhí)行結(jié)果：
a is main PID for parent before 2.sh:1162 using sourcing PID FOR 2.SH:1162 2.sh get a from main.sh is main`這里寫代碼片` now 2.sh a is 2.sh PID FOR parent after 2.sh :1162 now m
通過for循環(huán)，循環(huán)變量作為2.sh變量賦值并執(zhí)行。
#！main主函數(shù)
#!/bin/sh
a=0
for ((i=1; i<=10; i ++))
do
a=$i
echo "a is $a"
echo "PID for parent before 2.sh:$$"
echo "using sourcing"
source ./2.sh
echo "PID FOR parent after 2.sh :$$"
echo "now a is $a"
done
輸出結(jié)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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