Shell替换字符串的几种方法：变量替换，sed，awk

变量a是一个带空格的字符串，现在用"yezhou"替换变量a中的"appblog"：

$ echo $a
-rw-r----- 3 appblog appblog 3336 2012-01-12 17:35 /apps/appblog/properties/IMP_USE_PERSONALINFO.properties

#用变量替换${a//}做字符串替换
$ echo ${a/appblog/yezhou}    #变量a中的第一个匹配的字符串会被替换
-rw-r----- 3 yezhou appblog 3336 2012-01-12 17:35 /apps/appblog/properties/IMP_USE_PERSONALINFO.properties
$ echo ${a//appblog/yezhou}    #变量a中所有匹配的字符串都会被替换
-rw-r----- 3 yezhou yezhou 3336 2012-01-12 17:35 /apps/yezhou/properties/IMP_USE_PERSONALINFO.properties

#用sed做字符串替换
$ echo $a | sed 's/appblog/yezhou/'    #sed 's///' 用来替换第一个匹配的字符串
-rw-r----- 3 yezhou appblog 3336 2012-01-12 17:35 /apps/appblog/properties/IMP_USE_PERSONALINFO.properties
$ echo $a | sed 's/appblog/yezhou/g'    #sed 's///g'用来替换所有匹配的字符串
-rw-r----- 3 yezhou yezhou 3336 2012-01-12 17:35 /apps/yezhou/properties/IMP_USE_PERSONALINFO.properties

#用awk做字符串替换 （这个例子中用sub或gsub都可以，默认是空格为分隔符）
$ echo $a | awk '{gsub(/appblog/,"yezhou",$3);print $0}'    #指定替换第一个
-rw-r----- 3 yezhou appblog 3336 2012-01-12 17:35 /apps/appblog/properties/IMP_USE_PERSONALINFO.properties
$ echo $a | awk '{gsub(/appblog/,"yezhou");print $0}'    #全部替换
-rw-r----- 3 yezhou yezhou 3336 2012-01-12 17:35 /apps/yezhou/properties/IMP_USE_PERSONALINFO.properties