The initial version of shell scripting

1. Shell scripts are executed in a top-down, process-oriented order.

2. File name format: xxx.sh

3. First line of file content: #!/ bin/bash

4. Shell scripts are all about putting commands together.

5. define variables

Shell script variables are defined as: key=value, note: = can not have spaces on both sides

Static variable definition: a='www.ruozedata.com'

Dynamic variable definition: b=`date` #variable b is to get the current time, call b when the current time dynamically

The method that uses variables in shell scripts: ${variable}, if you use variable a, it should be ${a}.

6. if judged

Can judge: integer, decimal, string, folder exists, file exists, etc.

Format: if [space xx = yy space] Note: Use a single equal sign, with a space before, after and on both sides of the expression.

Examples:

if [ '$a' = 'www.ruozedata.com' ]; then

echo "D3"

fi

7. A few common ways to write for loop in shell

Category 1: Digital Cycle

Example 1:

#!/ bin/bash

for((i=1;i