. (source or dot operator)
SYNTAX . filename [arguments] source filename [arguments]
Read and execute commands from the filename argument in the current shell context.
If filename does not contain a slash, the
PATH variable is used to find filename. The current directory is searched if filename is not found in
If any arguments are supplied, they become the positional parameters when filename is executed. Otherwise the positional parameters are unchanged.
The return status is the exit status of the last command executed, or zero if no commands are executed. If filename is not found, or cannot be read, the return status is non-zero.
A period `.’ is a synonym for `source’
source is a bourne shell builtin and a POSIX `special’ builtin
Executing a script
[raja@AGRAJA~]$ source script_name
[raja@AGRAJA~]$ sh script_name
[raja@AGRAJA~]$ csh script_name
[raja@AGRAJA~]$ bash script_name