1.wc -l shows the number of lines in the file
wc -l test.txt shows the number of lines in the file
2.ls -l | wc -l shows the number of files in the directory
ls -l | wc -l shows the number of files in the directory
3.tail displays the end of the specified file
Example 1: Display the last 5 lines of the file tail -5 log2014.log
Example 2: Display the file from line 5 tail -n +5 log2014.log
Example 3: tail -f log2014.log This command keeps reading the latest content, so that it has the effect of real-time monitoring. Use Ctrl+c to terminate
4. head shows the beginning of the file
Example 1: Display the first n lines of the file head -5 log2014.log
Example 2: Display the first n bytes of the file head -c 20 log2014.log
Example 3: The contents of the file except the last n bytes head -c -32 log2014.log
Example 4: Output all the contents of the file except the last n lines head -n -6 log2014.log
5. cat connects the file string and sends it to the basic output
(1) Syntax: cat [option] [file]
-n or --number number all output lines starting from 1
-b or --number-nonblank is similar to -n, except that blank lines are not numbered
-s or --squeeze-blank When encountering a blank line with more than two consecutive lines, replace it with a blank line
(2) Example: cat -n textfile1> textfile2 Add the line number to the content of textfile1 and enter it into the file textfile2
cat -b textfile1 textfile2 >> textfile3 Add the line number to the content of textfile1 and textfile2 (blank lines are not added) and enter the content into the file textfile3
6.more view file content by page
Example 1: Display the content from line 3 in the file more +3 log2012.log
Example 2: Find the first line where the string "day3" appears in the file, and display the output from the first two lines more +/day3 log2012.log
Example 3: Set the number of lines displayed on each screen more -5 log2012.log
Example 4: List the files in a directory. Because there are too many contents, we should learn to use more to display them in pages. This has to be combined with the pipeline | ls -l | more -5