Shulou(Shulou.com)06/03 Report--

Use the two methods of the if statement to determine the size of two numbers.

The first kind:

If the number of #! / bin/basha=$1b=$2# parameters is not equal to 2, [$#-ne 2] & & {echo "USAGE:$0 NUM1 NUM2" exit 1} # calculate the return value expr $a + 0 & > / dev/nullRETVAL1=$?expr $b + 0 & > / dev/nullRETVAL2=$?# return value must all be 0 $? The return value of 0 from the previous command indicates that test $RETVAL1-eq 0-a $RETVAL2-eq 0 | {echo "Please enter input two" num "again." Exit 2} # compare if [$a-eq $b]; then echo "$a = $b" elif [$a-gt $b]; then echo "$a > $b" elif [$a-lt $b]; then echo "$a

< $b"else exitfi注：脚本在此页面可能有的字符会自动变成中文字符，如果贴出来运行有可能会报错，只能慢慢照着敲。 第二种 #!/bin/bashread -t 5 -p "Please enter input two num:" a b#判断是字符串长度是否等于零，如果等于零则为真[ -z "$a" ] || [ -z "$b" ]&&{ echo "Please enter input two num agagin." exit 1}#判断返回值的结果是否为trunexpr $a + 0 &>

/ dev/nullRETVAL1=$?expr $b + 0 & > / dev/nullRETVAL2=$?# determines whether the returned values are all truntest $RETVAL1-eq 0-a $RETVAL2-eq 0 | {echo "Please enter input two" num "again." Exit 2} # judge the size of if [$a-eq $b]; then echo "$a = $b" elif [$a-gt $b]; then echo "$a > $b" elif [$a-lt $b]; then echo "$a < $b" else exit 3fiexit Note: the possible characters of the script on this page will automatically become Chinese characters, if posted to run may report errors, can only be typed slowly.

Summary:

Learning scripts can only be practiced more, in order to slowly form a script thinking, otherwise you will never be able to write your own script.

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