What are the shell script functions?
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1 define function
Function fname () {
Statements; # inside the function
}
Or
Fname () {
Inside the statements;# function
}
2 call
$fname;# executes function
$fname arg1 arg2; # pass parameters
3 Parameter acquisition:
$1 first parameter $2 second parameter. Nth parameter of $n
$@ can represent "$1", "$2", "$3", etc., often representing parameters separated by spaces
$* can stand for "$1c$2c$3" where c is a character and treats all parameters as a single string, rarely applicable.
4 apply the function to the child shell: export-f fname
5 get the function return value: echo $?; # returns 0 indicates success. Non-zero is a failure.
6 date date command
Date-s "format date string"
Date "+% Y% B% d"; # print the corresponding format date: 2012 August 02
7 read read command
Read-n 2 var; # reads 2 characters and stores them in the var variable.
Read-s var; # does not echo what is read
Read-p "Engter input:" var; # displays prompt messages
Read-t 3 var; # reads for the variable var in 3 seconds.
Read-d ":" var # ends the input line with a delimiter.
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