test 命令： （鸟哥linux私房菜视频第30集）
test -d ： 判断一个文件是否为目录。
eg: test -d passwd && echo "is a dir"|| echo "is not a dir"
test -f ： 判断一个文件是否为普通文件。
eg: test -f sh01.sh && echo "is a regular file" || echo "is not a regular file"
test -e ：判断一个文件是否存在。
eg: test -e sh06.sh && echo "the file exits" || echo "the file does not exit"
test -b: 判断一个文件是否为块设备文件。
eg： test -b /dev/root && echo "is a block device" || echo "is not a block device"
test -p: 判断一个文件是否为管道文件。
eg：test -p /dev/log && echo "is a FIFO file" || echo "is not a fifo file"
test -S: 判断一个文件是否为套接字文件。
eg： test -S /dev/log && echo "is a socket file" || echo "is not a socket file"
test -s: 判断一个文件是否存在或文件大小是否大于0。
eg： test -s sh06.sh && echo "exit or size > 0" || echo "not exit or size <=0"
test -r/w/x + filename: 判断一个文件是否可读/写/执行。
test -r sh01.sh && echo "readable" ||echo "unreadable"
test -u + filename: 判断一个文件是否设置了uid。
test -u sh01.sh && echo "set uid"|| echo "have not set uid"
test file1 -nt file2 : 判断file1 是否比file2 更新。
test sh02.sh -nt sh01.sh && echo "newer" || echo "not newer"
test file1 -ot file2 : 判断file1 是否比file2 更旧。
test sh01.sh -ot sh02.sh && echo "old" || echo "not old"
test file1 -ef file2 : 判断file2 是否为file2 的硬链接。
eg: test sh01.sh -ef sh01-hard && echo "hardlink" || echo "not hardlink"
两个整数之间的判断：
test n1 -eq n2
-eq: 两数值相等。（equal）
-ne:两数值不等（not equal）
-gt:n1 大于n2（greater than）
-lt:n1 小于n2 (less than）
-ge:n1 大于等于n2 (greater than or equal ）
-le: n1小于等于n2 ( less than or equal ）
eg:
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ n1=5
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ n2=6
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$n1" -eq "$n2" && echo "equal" || echo "not equal"
not equal
判定字符串数据：
test -z string 判定字符串是否为0？若string为空字符串，则为true
test -z string 判定字符串是否为非0？若string为空字符串，则为fasle，否则为ture。 -n可省略
test str1 = str2 判定str1是否等于str2，若相等，则回传true（=两边需要空格）
test str1 ！= str2 判定str1是否不等于str2，若相等，则回传false
eg:
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ str=""
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test -z "$str" && echo "is null" || echo "is not null"
is null
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test -n "$str" && echo "is not null" || echo "is null"
is null
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" && echo "is not null" || echo "is null"
is null
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ str="abc"
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" && echo "is not null" || echo "is null"
is not null
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" && echo "is not null" || echo "is null"
is not null
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ str1="avc"
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ str1="abc"
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" = "$str1" && echo "equal" ||echo "not equal"
equal
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ ^C
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" = "$str1" && echo "equal" ||echo "not equal"
equal
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test "$str" != "$str1" && echo "not equal" ||echo " equal"
equal
多重条件判定：例如： test -r filename -a -x filename
eg:
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test -r sh01.sh -a -x sh01.sh && echo "readable and excutable" || echo "no"
readable and excutable
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ chmod 444 sh03.sh
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test -r sh03.sh -a -x sh03.sh && echo "readable and excutable" || echo "no"
no
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test -r sh03.sh -o -x sh03.sh && echo "readable or excutable" || echo "no"
readable or excutable
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test ! -x sh03.sh && echo "is not excutable" || echo "excutable"
is not excutable
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test ! -r sh03.sh && echo "is not readable" || echo "readable"
readable
qinshizhi@holadev-system:/mnt/workdir/qinshizhi$ test ! -w sh03.sh && echo "is not writeable" || echo "writeable"
is not writeable