shell编程系列1--shell脚本中的变量替换变量替换总结：1、${变量#匹配规则}    # 从头开始匹配，最短删除2、${变量##匹配规则}    # 从头开始匹配，最长删除(贪婪模式)3、${变量%匹配规则}    # 从尾开始匹配，最短删除4、${变量%%匹配规则}    # 从尾开始匹配，最长删除(贪婪模式)5、${变量/旧字符串/新字符串}    # 替换变量内的旧字符串为新字符串，只替换第一个6、${变量//旧字符串/新字符串}    # 替换变量内的旧字符串为新字符串，全部替换variable_1="i love you,do you love me"举例：[root@localhost ~]# variable_1="i love you,do you love me"[root@localhost ~]# echo $variable_1i love you,do you love me# 从头开始删除，只删除第一个ov及ov以前的字符串[root@localhost ~]# var1=${variable_1#*ov}[root@localhost ~]# echo $var1e you,do you love me# 从头开始删除，最长删除ov及ov以前的字符串[root@localhost ~]# var2=${variable_1##*ov}[root@localhost ~]# echo $var2e me# 从尾部删除最短匹配的ov及ov后面的字符串[root@localhost ~]# var3=${variable_1%ov*}[root@localhost ~]# echo $var3i love you,do you l# 从尾部删除最长匹配的ov及ov后面的字符串[root@localhost ~]# var4=${variable_1%%ov*}[root@localhost ~]# echo $var4i l# 替换第一个小写的bin为大写的BIN[root@localhost ~]# echo $PATH/usr/local/go/bin:/data/golang_project/bin:/usr/java/jdk1.8.0_181-amd64/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin[root@localhost ~]# var5=${PATH/bin/BIN}[root@localhost ~]# echo $var5/usr/local/go/BIN:/data/golang_project/bin:/usr/java/jdk1.8.0_181-amd64/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin# 替换所有小写的bin为大写的BIN[root@localhost ~]# var6=${PATH//bin/BIN}[root@localhost ~]# echo $var6/usr/local/go/BIN:/data/golang_project/BIN:/usr/java/jdk1.8.0_181-amd64/BIN:/usr/local/sBIN:/usr/local/BIN:/usr/sBIN:/usr/BIN:/root/BIN