本文實例為大家分享了Linux定義變量腳本，供大家參考，具體內容如下

現有兩段基本一樣的代碼，只是變量進行改變，其他都沒有變化，但是執行過程中出現了不一樣的結果

代碼一：

vi back.sh#backup import file,such as /etc/rc.local /var/spool/cron/rootIP=$(ifconfig eth1|sed -nr '2s#.*addr:(.*) B.*#/1#gp')Path=/backupif [ $(date +%w) -eq 0 ]then  Time=$(date +%F-%w -d "-1 day")else  Time=$(date +%F "-1 day")fimkdir $Path/$IP -pcd / &&/tar zcfh $Path/$IP/backup_$Time.tar.gz var/spool/cron/root etc/rc.local etc/sysconfig/iptables var/www/html app/logs &&/md5sum $Path/$IP/backup_$Time.tar.gz >$Path/$IP/flag_$Time.log &&/rsync -azv $Path/ rsync_backup@172.16.1.41::backup --password-file=/etc/rsyncd.password &&/find $Path/ -type f /( -name "*.log" -o -name "*.tar.gz" /) -mtime +7 |xargs rm –f"back.sh" 15L, 628C written

代碼二：

vi back.sh#backup import file,such as /etc/rc.local /var/spool/cron/rootIP=$(ifconfig eth1|sed -nr '2s#.*addr:(.*) B.*#/1#gp')Path=/backupif [ $(date +%w) -eq 0 ]then  Time=$(date +%F-%w -d "-1 day")else  Time=$(date +%F "-1 day")fimkdir $Path/$IP -pcd / &&/tar zcfh /backup/$IP/backup_$Time.tar.gz var/spool/cron/root etc/rc.local etc/sysconfig/iptables var/www/html app/logs &&/md5sum $Path/$IP/backup_$Time.tar.gz >$Path/$IP/flag_$Time.log &&/rsync -azv $Path/ rsync_backup@172.16.1.41::backup --password-file=/etc/rsyncd.password &&/find $Path/ -type f /( -name "*.log" -o -name "*.tar.gz" /) -mtime +7 |xargs rm –f"back.sh" 15L, 628C written

上面代碼只是修改了打包的情況，tar zcf /backup和定義一個變量tar $Path/結果就出現不一樣的情況，第一種執行結果是：

代碼一執行結果：

[root@nfs01 backup]# ls
172.16.1.31 backup_2017-12-23-6.tar.gz flag_2017-12-23-6.log

代碼二執行結果：

[root@nfs01 backup]# ls
172.16.1.31

代碼一和代碼二原理是一樣的，但是為什么執行的結果卻有差別呢？個人覺得就是環境變量的目錄的開頭引起的，這樣讓前面的環境變量失效了，打包了兩次：

測試腳本

[root@nfs01 scripts]# sh -x back.sh ++ sed -nr '2s#.*addr:(.*) B.*#/1#gp'++ ifconfig eth1+ IP=172.16.1.31+ Path=/backup++ date +%w+ '[' 4 -eq 0 ']'++ date +%F -d '-1 day'+ Time=2017-12-20+ mkdir /backup/172.16.1.31 -p+ cd /+ tar zcfh /backup/172.16.1.31/backup_2017-12-20.tar.gz var/spool/cron/root etc/rc.local etc/sysconfig/iptables var/www/html app/logs+ md5sum /backup/172.16.1.31/backup_2017-12-20.tar.gz+ rsync -azv /backup/ rsync_backup@172.16.1.41::backup --password-file=/etc/rsyncd.passwordsending incremental file list172.16.1.31/backup_2017-12-20.tar.gz172.16.1.31/flag_2017-12-20.logsent 1128 bytes received 65 bytes 2386.00 bytes/sectotal size is 2960 speedup is 2.48+ xargs rm -f+ find /backup/ -type f '(' -name '*.log' -o -name '*.tar.gz' ')' -mtime +7