[Android]Linux BASH腳本中cmp比較命令的應用例子

使用例子： cmp -s sysfs-tty sysfs-ptp echo $? 1 cmp -s sysfs-tty sysfs-tty echo $? 0

說明： sysfs-tty, sysfs-ptp是文件名， echo $?會輸出上一條命令的執行結果，1表示比較的兩個文件內容不一樣， 0 表示比較的兩個文件內容相同。 比較內容是文件的二進制內容。

基於此，能夠在bash 腳本里，根據比較結果來作不一樣的動做： cmp -s sysfs-tty sysfs-ptp if [ "$?" -ne 0 ]; then #若是不相同或比較失敗，則從新拷貝等 else #若是相同，則不作。。。 fi

cmp 命令說明： Usage: cmp [OPTION]... FILE1 [FILE2 [SKIP1 [SKIP2]]] Compare two files byte by byte.

-b --print-bytes Print differing bytes. -i SKIP --ignore-initial=SKIP Skip the first SKIP bytes of input. -i SKIP1:SKIP2 --ignore-initial=SKIP1:SKIP2 Skip the first SKIP1 bytes of FILE1 and the first SKIP2 bytes of FILE2. -l --verbose Output byte numbers and values of all differing bytes. -n LIMIT --bytes=LIMIT Compare at most LIMIT bytes. -s --quiet --silent Output nothing; yield exit status only. -v --version Output version info. --help Output this help.

SKIP1 and SKIP2 are the number of bytes to skip in each file. SKIP values may be followed by the following multiplicative suffixes: kB 1000, K 1024, MB 1,000,000, M 1,048,576, GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y.

If a FILE is `-' or missing, read standard input. Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.