Echo in shell is similar to the echo in PHP which all output string.The syntax for echo is:
echo string
You can use echo to achieve more complex output format control.
1. Display ordinary string:
echo "It is a test"
The double quotes here can be omitted,the following command has the same effect as the above example.
echo It is a test
2. Display escape characters
echo "\"It is a test\""
output:
"It is a test"
Similarly, double quotes can also be omitted.
3. Display variables
The read command reads a line from standard input and assigns the value of each field of the input line to a shell variable.
#!/bin/sh
read name
echo "$name It is a test"
Save the above code to the file “test.sh”,and the name receives the variable from the standard input and output will be
[root@www ~]# sh test.sh
OK #standrad input
OK It is a test #output
4. Display line breaks
echo -e "OK! \n" # -e turn on escaping
echo "It is a test"
output:
OK!
It is a test
5. Display no wrap
#!/bin/sh
echo -e "OK! \c" # -e turn on escaping \c no wrap
echo "It is a test"
output:
OK! It is a test
6. Display results to a file directly
echo "It is a test" > myfile
7. Output the string as is, without escaping or taking variables (using single quotes)
echo '$name\"'
output:
$name\"
8. Display command execution results
echo `date`
Notice:Back quotes(`) are used here, not single quotes(‘).
The result will show the current date
Mon Apr 20 21:04:54 CST 2020