變量a是一個帶空格的字符串，現在用"hdpusr400"替換變量a中的"hduser302"：
1 [liusiyi@localhost ~]$ echo $a 2 -rw-r----- 3 hduser302 hduser302 3336 2019-07-12 17:35 /apps/hduser302/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 3 4 #用變量替換${a//}做字符串替換 5 [liusiyi@localhost ~]$ echo ${a/hduser302/hdpusr400} #變量a中的第一個匹配的字符串會被替換 6 -rw-r----- 3 hdpusr400 hduser302 3336 2019-07-12 17:35 /apps/hduser302/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 7 [liusiyi@localhost ~]$ echo ${a//hduser302/hdpusr400} #變量a中所有匹配的字符串都會被替換 8 -rw-r----- 3 hdpusr400 hdpusr400 3336 2019-07-12 17:35 /apps/hdpusr400/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 9 10 #用sed做字符串替換 11 [liusiyi@localhost ~]$ echo $a | sed 's/hduser302/hdpusr400/' #sed 's///' 用來替換第一個匹配的字符串 12 -rw-r----- 3 hdpusr400 hduser302 3336 2019-07-12 17:35 /apps/hduser302/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 13 [liusiyi@localhost ~]$ echo $a | sed 's/hduser302/hdpusr400/g' #sed 's///g'用來替換所有匹配的字符串 14 -rw-r----- 3 hdpusr400 hdpusr400 3336 2019-07-12 17:35 /apps/hdpusr400/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 15 16 #用awk做字符串替換 （這個例子中用sub或gsub都可以，默認是空格為分隔符） 17 [liusiyi@localhost ~]$ echo $a | awk '{gsub(/hduser302/,"hdpusr400",$3);print $0}' #指定替換第一個 18 -rw-r----- 3 hdpusr400 hduser302 3336 2019-07-12 17:35 /apps/hduser302/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties 19 [liusiyi@localhost ~]$ echo $a | awk '{gsub(/hduser302/,"hdpusr400");print $0}' #全部替換 20 -rw-r----- 3 hdpusr400 hdpusr400 3336 2019-07-12 17:35 /apps/hdpusr400/student/properties/xxyy/IMP_00004_XXYY_USE_PERSONALINFO.properties
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