Linux file system, redirection and summary of common commands

First, common commands

Touch command: Touch [OPTION] ... FILE ...-a:atime-m:mtime-c:ctimeaccess, modify, change three timestamp differences: Access time, Atime, read its content through cat, more, etc. modify: Modify Time , Mtime, change the contents of the file changes: Change the time, CTime, change the file metadata, that is, modify the permissions, belong to the group, belong to the master, etc.

Use the stat command to view a file with three timestamps as follows:

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CP command: CP [OPTION] ... [-T] SOURCE DEST CP [OPTION] ... SOURCE ... Directory CP [OPTION] ...-t DIRECTORY SOURCE ...    Common options:-r: Recursively copy all contents of directory and Content-A: archive-D: Indicates that the source file pointed to by the symbolic link is not tracked, directly copy the link file-P: Keep the property information of the original file-F: Force override-V: Display process-r: Recursively copy directory and all internal content -I: Interactive-preserv=[...] mode: Permissions ownership: Genus Group Timestramp: timestamp

1. If the destination file does not exist, create a target file to copy the contents of the source file to the new target file.

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2. If the target file exists, then prompt to overwrite the contents of the target file

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The following indicates that the user is not prompted to overwrite: \CP chen.txt/testdir/test /USR/BIN/CP chen.txt/testdir/test                             

1, using the alias command, the daily/etc/directory of all files, backup to/testdir/under the new directory, and require the new directory format is BACKUPYY-MM-DD, the backup process is visible

Alias cp= ' cp–av/etc/testdir/backup ' date +%f '

2, first create the/testdir/rootdir directory, and then copy the/root all the next file into the directory, and ask to retain the original permissions

cp/root/-R--preserv=mode/testdir/rootdir or: cp-av/etc/testdir/backup$ (date)

MV Command: Common options:-I: Interactive-f: Force RM Command: Common options:-I: Interactive-F: Forced-r: Recursive

Tree command:-D: Show only Directories-L level: Specifies the number of levels displayed tree–l 2/etc/-P pattern: Displays only the path that is matched by the specified pattern-p: Show permissions

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mkdir Create Directory-P: exists in no error, and can automatically create the required directories;-V: Show details-M MODE: Specify the permissions directly when creating the directory;

RmDir Delete Empty directory-P: Recursive Delete parent Empty directory-V: Show details rm-r recursively delete directory tree

(1) How to create/testdir/dir1/x,/testdir/dir1/y,/testdir/dir1/x/a,/testdir/dir1/x/b,/testdir/dir1/y/a,/testdir/dir1/y/b

MKDIRI–P/TESTDIR/DIR1/{X/{A,B},Y/{A,B}}

(2) How to create/testdir/dir2/x,/testdir/dir2/y,/testdir/dir2/x/a,/testdir/dir2/x/b

Mkdir-pv/testdir/dir2/{x/{a,b},y}

(3) How to create/TESTDIR/DIR3,/TESTDIR/DIR4,/TESTDIR/DIR5,/TESTDIR/DIR5/DIR6,/TESTDIR/DIR5/DIR7

mkdir–p/testdir/dir{3,4,5/dir{6,7}}

MKDIR–P/TESTDIR/{DIR3,DIR4,DIR5/{DIR6,DIR7}}

Files can contain multiple types of data-checking file types, and then determine the appropriate open command or application using file [Options]<filename>    Option:-B The file name is not displayed when the file identification results are listed. -C verbose display of the instruction execution process, easy to debug or parse the program execution-F list File name file type-F with the specified delimiter symbol to replace the output file name after the default ":" Delimiter-I output MIME type string-l view the corresponding soft link file type- Z try to interpret the contents of the compressed file--help display command online Help

Second, redirect

Standard input and output: Program: Instruction + Data read-in data: Input output data: Outputs open files have a Fd:file descriptor (file descriptor) Linux gives the program three I/O devices standard input (STDIN)-0 Default accept input standard output from keyboard (STDOUT)-1 Default output to terminal window standard error (STDERR)-2 default output to terminal window I/O redirection: Changing the default location supported operation symbols include: > redirect output to file 2> redirect error output to file &> Redirect all output to File > file contents will be overwritten # Set-c: Prevents content from overwriting existing files, but can append mandatory overrides: >| # set +c: Allow overwrite >> original content, append content > File content will be overwritten # Set-c: Prevents overwriting of existing files, but can append mandatory overrides: >| # set +c: Allow overlay >> original content, append content

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Linux file system, redirection and summary of common commands