Use command to view partial lines of log file in Linux

[1] Starting from line 3000, display 1000 lines. That is, rows 3000~3999

cat filename | tail -n 3000 | head -n 1000

【二】Display lines 1000 to 3000

cat filename| head -n 3000 | tail -n 1000

*Note the order of the two methods

break down:

tail -n 1000: Display the last 1000 lines
tail -n 1000: Start displaying from line 1000, and display
after line 1000 Head -n 1000: Display the first 1000 lines

【三】Use sed command

sed -n '5,10p' filename This way you can only view lines 5 to 10 of the file.

Linux statistics file line number

Syntax: wc [options] file...

Description: This command counts the number of bytes, words, and lines in a given file. If no filename is given, then standard input is read. wc also gives a total count of all specified files. Words are the largest string of characters separated by space characters.

The meaning of each option of this command is as follows:

　-c counts the number of bytes.
- l counts the number of rows.
- w counts the number of words.

These options can be used in combination.

The order and number of output columns are not affected by the order and number of options.

Always displayed in the following order and with a maximum of one column per item.
Number of lines, number of words, number of bytes, file name
If there is no filename on the command line, the filename does not appear in the output.

For example:

$ wc - lcw file1 file2
4 33 file1
7 52 file2
11 11 85 total

Example analysis:

1. Statistics of the number of js files in the demo directory:
find demo/ -name "*.js" |wc -l
2. Count the code lines of all js files in the demo directory:
find demo/ -name "*.js" |xargs cat|wc -l or wc -l `find ./ -name "*.js"`|tail -n1
3. Count the code lines of all js files in the demo directory, and filter out empty lines:
find /demo -name "*.js" |xargs cat|grep -v ^$|wc -l

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