Linux Shell Programming II

With "'"""todayis"  ' date ' preceded by a character, followed by ' date ' Represents the Execute Date command. PDATE=""'date'is         Date

" Expr " is used to calculate the result of a=9b=tenvar1= $a +$becho $var 1 output is "9 +10"expr" is used to take the result of the calculation var1= ' expr $a + $b ' NOTE: " + " space is required before and after
All variables in the shell syntax are strings, and if you want to participate in the operation, you must use the command

Linux Shell Programming II