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小編給大家分享一下shell如何實(shí)現(xiàn)for循環(huán)、循環(huán)變量值付給其他shell腳本,希望大家閱讀完這篇文章之后都有所收獲,下面讓我們一起去探討吧!
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(gè)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(gè)腳本:
在運(yùn)行shell腳本時(shí)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(huì)繼承當(dāng)前shell的環(huán)境變量。但事實(shí)上exec產(chǎn)生了新的進(jìn)程,他會(huì)把主shell的進(jìn)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(huì)執(zhí)行。
2、source(source /home/script.sh)
使用source或者“.”來調(diào)用外部腳本,不會(huì)產(chǎn)生新的進(jìn)程,繼承當(dāng)前shell環(huán)境變量,而且被調(diào)用的腳本運(yùn)行結(jié)束后,它擁有的環(huán)境變量和聲明變量會(huì)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(yùn)行。
3、fork(/home/script.sh)
直接運(yùn)行腳本,會(huì)以當(dāng)前shell為父進(jìn)程,產(chǎn)生新的進(jìn)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(huì)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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