ma series -21-bash function function call function return value

 

 

0 Structured programming, cannot run independently, execute when it needs to be called, can be called multiple times,

Calling a function:
Just use the function name directly.

 

1 Definition:

 

Way 1:
function FUNCNAME {
  command
}
Way 2:
FUNCNAME() {
  command
}

 

2 Custom function return value:

 

return #The
return value is between 0-255, as long as return, the function will exit

 

The difference from $?:

The return value of $? depends on the execution result of the last command in the script. If you define a function, various errors are reported in the function, but the last line echo 11, then the result returned by echo $? must be 0.

 

And return # is a custom return value.

 

3 cases:

 

eg1:
#!/bin/bash
#
TWOSUM() {
echo ${$1+$2}
}
SUM=`TWOSUM 1 2` pass parameters to the function and execute
echo $SUM

eg2:
#!/bin/bash
#
ADDUSER() {
USERNAME=hadoop
	if !id -u $USERNAME &> /dev/null; then
	useradd $USERNAME
	echo $USERNAME | passwd --stdin $USERNAME &> /dev/null
	return 0 defines the return value of the function
	else
	return 1
	be
}

ADDUSER calls this function
if [$? -eq 0]; then output the status bits of the previous line of execution
	echo "add user finished"
else 	
	echo "failuer"
be	

eg3:
#!/bin/bash
#
ADDUSER() {
USERNAME=$1
	if !id -u $USERNAME &> /dev/null; then
	useradd $USERNAME
	echo $USERNAME | passwd --stdin $USERNAME &> /dev/null
	return 0    
	else
	return 1
	be
}

for I in {1..10}; do
ADDUSER user$I
if [$? -eq 0]; then  
	echo "add user$I finished"
else 	
	echo "add user$I failuer"
be	
done