1. Introduction to Programming:
Early Programming: driving the hardware can not be used when the default;
The need for communication between different manufacturers instruction hardware devices, drivers we need to "translate";
More close and hardware development engineers, to learn "assembly language"; and "assembly language" is limited by the manufacturers; CC ++ is the underlying assembly language;
Now programming: based on high-level language, as well as ultra-high-level language, better enable programmers to achieve programming;
Programming languages Category:
High-level language, and language needs ultra-high * * translated into computer-readable language (binary instructions)
Interpreted - translated line by line, line by line shell python Java
Program instructions = data +
Object-oriented - focusing on the data programming language
Process for the focus on instruction ---
Implementation programming language line by line :()
1. executed sequentially
2. loop execution - * for the while untile
3. Choose Execute - branch
add user
IF ID * & $> / dev / null; the then
echo "This user has there is "
the else
for i in $ *; do
userass $ i
echo" 123456 "| passwd --stdin" $ i "&> / SeV / null
echo" $ i user added successfully "
DONE
Exit 0
fi
2.shell scripting language introduced
3. variables