You can use the cat command to see the content of a file and display the line numbers by using the -b option along with the cat command as follows
cat -b filename
You can use the wc command to get a count of the total number of lines, words, and characters contained in a file.
wc filename
To make a copy of a file use the cp command.
cp source_file destination_file
To go in your last directory
cd -
To list the files in a directory
ls dirname
An important Unix concept is the environment, which is defined by environment variables. Some are set by the system, others by you, yet others by the shell, or any program that loads another program.
A variable is a character string to which we assign a value. The value assigned could be a number, text, filename, device, or any other type of data. For example, first we set a variable TEST and then we access its value using the echo command
TEST="Unix Programming" echo $TEST
It produces the following result.
Unix Programming
If we don‘t use the $ sign, it returns
TEST
Really clear a terminal instead of simply shifting previous output upwards when you run "clear" command.
tput reset
原文地址：https://www.cnblogs.com/cxxszz/p/8573773.html