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–> Linux commands

The grep command

Grep the Global Regular Expression Print (grep) command is used to search for qualified strings in a file. By default, the qualified line is displayed.

Common parameters:

-c: number of lines (count) -a < number of lines > : displays the content after the target line (after) -b < number of lines > : displays the content before and after the target line (before) -c < number of lines > : displays the content before and after the target line (context) -d: displays the content before and after the target line (context) -e< rule > : Regular expression search (regexp) -i: ignore case (ignore case) -n: Line number for directoriesCopy the code
  1. Find the specified field in the file:
Grep 'Found string' file nameCopy the code
  1. Find the specified field in the file and count The Times:
Grep -c 'search string filename grep' search string filename | wc -lCopy the code

B: before the pipeline operators’ | ‘can be a command from the standard output information correctly, as a standard input is passed to the next command; Wc -l: indicates the wc command. The -l parameter displays the number of lines.

  1. Display the content before and after the target line:
Grep -a10-b5 'Search string' file nameCopy the code
  1. The system alarm shows the time, but the log file is too large to be viewed directly by CAT: (*.log can be found in all files with the suffix log)
    grep -n '2019-10-24 00:01:11' *.log
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The find command

Find command: finds files in the specified directory.

  1. The find command defaults to finding subdirectories and files in the current directory:
    find *.log
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The top and ps commands

Ps command (process status) : displays the status of the current process.

  1. Display all processes:
    ps -A / ps -e
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  1. Display all processes in full format:
    ps -ef
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  1. Specify a process name to find all processes that contain Java:
    ps -ef | grep 'java'
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The top command: Can monitor progress in real time and display a summary of the system.

The difference between the ps command and the top command:

  • Ps process information is the process information immediately after the command is executed, while TOP can be continuously monitored.
  • Ps focuses on what needs to be viewed;
  • Top focuses on CPU and memory usage.

The sort command

Sort command: enables you to sort the contents of a file by line.

Common parameters:

-b: ignores the space before the line when sorting. -f: ignores the case difference in sorting. -n: Sort by value size. -r: Sort in reverse order. -u: output the result after deduplication. -o: outputs the specified file as the sorting result.Copy the code
  1. Forward sort/reverse sort:
    sort -n file.log
    sort -nr file.log
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Tail and head commands

  1. Look at the first/last few lines of the file:
    head -n 10 file.log
    tail -n 10 file.log
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  1. View the appended content at the end of the file in real time:
    tial -f file.log
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ls&cd&mkdir&rm

Basic command set:

Ls -lhrt Time change by easy-to-read mode Display file details in reverse order CD - Go to the last working path mkdir file Create a folder named file in the current directory mkdir -p/TMP /test/file Create the /test/file directory in TMP (-p can create multiple directories at a time) rm -rf file Delete all files in file directory and subdirectories mv test.log test. TXT Change the file name to test. TXT mv Log/TMP Move the test.log file to/TMP cp -r/TMP /file/TMP /file Copy the files in/TMP /file to a new directory/TMP /file cat -n test.log Display the entire file information (-n Displays the line number.) cat > test.log Creates a test.log fileCopy the code