#!/bin/bash echo "1" echo "2" echo "3" echo "4" echo "5" echo "6"
The shell above will print 1-6 in turn
Suppose we want to print only 5 and 6, and we want to comment out 1-4, except for the normal practice of adding # in front of each line
1、 Add comments manually
We can also use a clever way, or we can write the following
#!/bin/bash :<<EOF echo "1" echo "2" echo "3" echo "4" EOF echo "5" echo "6"
A colon is a command in the shell, which means to do nothing
: > data.log Equivalent to cat / dev / null > data.log It can clear the contents of the file
You can also append 1-4 input redirection to the black hole
#!/bin/bash cat >/dev/null<<EOF echo "1" echo "2" echo "3" echo "4" EOF echo "5" echo "6"
2、 Batch annotation with VIM
1. Block selection mode
First, open the script we want to operate with vim,
Then move the cursor to the first line we want to operate (here we move to the left of echo “1”) and press V to enter the — visual — mode
Then use the up and down keys to select the number of lines to be commented (here we use the down key to move to the line echo “4”)
Then press Ctrl + V (Ctrl + Q under win) to enter column mode
Press capital “I” to enter the insert mode, enter the comment character “#” or “/ /”, and then immediately press ESC (twice)
The final effect is as follows
Enter the block selection mode with Ctrl + V and select the comment symbol at the beginning of the line you want to delete. Note / / you need to select two,
After selecting, press D to delete the comment
Method 2: replace the command
Use the following command to add a comment at the beginning of the specified line:
: start line number, end line number s / ^ / annotator / g
Here we are going to operate lines 2 to 5, so after opening the script with VIM, enter
Then press enter to complete the replacement
: start line number, end line number s / ^ annotator / / g
Here we use
The above is the details of how to batch comment and cancel comment in shell. For more information about shell comment, please pay attention to other related articles in developer!