This is the fourth day of my participation in Gwen Challenge

File search command

find

  • Command name: find
  • Execute permission: all users
  • Function: File search
  • Grammar:Find [search scope]

Example 1, find by filename:

  • Find the file init in the directory /etc:

    find /etc -name init
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    • Unlike Windows, Linux searches for init and only returns files with the name init, but Windows searches for files with the name init.

    • You can use -etec/ -OK to perform operations on the search results, such as finding the inittab file under /etc and displaying its details

      find /etc -name inittab -exec ls -l {} \;
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      • {} indicates a substitution for the result
      • \ indicates an escape character
      • ; End of the said

  • If you want to find a file containing init like Windows, do as follows:

    find /etc -name *init*
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    • Use wildcards

  • Using -iname to search is case insensitive

    find /etc -iname init???
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    • Both initabc and initabc files will be searched
    • Use regular expressions to search

Example 2: Find by file size:

  • Find files larger than 100MB in the root directory

    find / -size +204800
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  • Add a few query criteria (not only for size) :

    • -a: Both search conditions are met
    • -o: Meet either of the two conditions
    • For example, search for files between 80MB and 100MB in /etc
    find /etc -size +163840 -a -size -204800
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    • -type: searches by file type

      • F: file

      • D: directory

      • L: Soft link file

      • For example, find a file whose file name starts with init and whose type is directory in /etc

        find /etc -name init* -a type -d
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    • -inum: Searches based on node I

      • Each file has an I node, which can be viewed through ls -i.

      • For example, there is a file whose I node is 31531

        find . -inum 31531 -exec rm {} \;
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Example 3: Find by owner:

  • Find the file with the owner AAA under /home:

    find /home -user AAA
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    • -group: searches by group

Example 4: Find by modification time:

  • Look for files and directories whose properties have been modified in the last 5 minutes under /etc

    find /etc -cmin -5
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    • about- 5: The minus sign indicates how long it will take, and the plus sign indicates how long it will take
    • -cmin: search by file attribute (change)
      • Such as throughls -ld /home/AAAYou can see the file properties
    • Add additional find options:
      • -amin: Search by access time
      • -mmin: search by file content (modify)

locate

  • Command name: locate
  • Execute permission: all users
  • Function: Find files in the file database
  • Grammar:Locate the file name

Note 1: The Locate search is fast because it periodically collects files into a file repository. So it searches directly in the database, and therefore faster than find.

Note 2: Sometimes locate does not find a file because the file has not yet been searched into the file database. You can use updatedb to update the database.

Note 3: Locate cannot be found if the file is in/TMP, even if you use updatedb

Note 4: If you want to be case-insensitive in lookups, you can add the use of -i. For example, locate -i helloworld.txt

which

  • Command name: which
  • Execute permission: all users
  • Run the following command to search for the directory where a command resides and the alias information
  • Grammar:Which command

Note 1: The commands stored in /bin/usr/bin are available to all users. The commands stored in /sbin /usr/sbin are available to the root user.

Example:

/usr/sbin/useradd /usr/sbin/useradd /usr/sbin/useraddCopy the code

whereis

  • Command name: whereis
  • Execute permission: all users
  • Run the following command to search for the directory where a command resides and the help file path
  • Grammar:Whereis [command name]

grep

  • Command name: grep
  • Execute permission: all users
  • Function: Search a file for a string matching line and output it
    • -i: case insensitive
    • -v: excludes the specified string
  • Grammar:Grep -iv [string] [file]

The sample

root@atomy-virtual-machine: /home/atomy/desktop # grep DisableMBIMGlobal /etc/usb_modeswitch.conf DisableMBIMGlobal=0Copy the code

Note 1: most of the time there are # comments in the file. The commented code does not take effect. We can use -v to exclude a specified character, for example

grep -v # /etc/usb_modeswitch.conf 
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But you can’t seem to find the information. Because there are so many # s in the file, valid lines sandwiched between them are also excluded. You can use

grep -v ^# /etc/usb_modeswitch.conf
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^ is a type of regular expression that indicates what to start with. The real power of grep lies in this. Grep and regular expression can find effective information well.

The help command

man

  • Command name: man
  • Original meaning: manual
  • Execute permission: all users
  • Function: Get help information
  • Grammar:Man [command or configuration file]
    • (space) or f turn the page
    • B Turn the page down
    • Line feed (Enter)
    • Q or Q exits

Example: View the help information about the ls command

man ls
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Example: View help information about configuration file services

man services   
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help

  • Command name: help
  • Execute permission: all users
  • Function: Obtain help information about Shell built-in commands
  • Grammar:The help command

Example: View the help information of the umask command

help umask   
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Decompression command

gzip

  • Command name: gzip
  • GNU zip
  • Execute permission: all users
  • Function: Compress files
    • Compressed file format:.gz
  • Grammar:Gzip [file]

gunzip

  • Command name: gunzip
  • GNU unzip
  • Execute permission: all users
  • Function: Decompress the. Gz compressed file
    • Only files can be compressed, not directories
  • Grammar:Gunzip [compressed file]

tar

  • Command name: tar

  • Execute permission: all users

  • Syntax: tar option [-zcf] [compressed file name] [directory]

  • Function: package directory, compressed file format:.tar.gz

    • – c: packaging
    • -v: Displays detailed information
    • -f: Specifies the file name
    • -z: package and compress
    • – x: unpack

Example: compression

I have a file tartext.txt in tartest folder in TMP. I’m now compressing the directory.

Package and compress the directory tartest as a.tar.gz file

tar -zcf tartest.tar.gz tartest
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Example: Decompress

root@atomy-virtual-machine:/tmp# tar -zxvf tartest.tar.gz
tartest/
tartest/tartest.txt
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zip

  • Command name: zip
  • Execute permission: all users
  • Function: Compress files or directories
    • The compressed file format is.zip
  • Grammar:Zip option [-r] [compressed file name] [file or directory]
    • -r Indicates the compressed directory

Example: Compressed file

zip tartest.txt.zip tartest.txt
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Example: Compressed directory

zip tartest.zip tartest
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unzip

  • Command name: unzip
  • Execute permission: all users
  • Function: Decompress the. Zip file
  • Grammar:Unzip [compressed file]

bzip2/bunzip2

  • Syntax: bzip2 option [-k] [file]

    • -k Saves the compressed file after it is generated
    • The compressed file format is.bz2

  • Syntax: bunzip2 option [-k] [zip file]

    • -k Retain the original file after decompressing it