Linux common commands [command] touch

touch - change file timestamps

touch [filename] is the "touch" at the file, if the file does not exist, create a new file; if the file exists, it is time to change the access atime file timestamps and other information.

 

Syntax:
　　Touch [OPTION] ... FILE ...

　　Touch [- ACFM ] [- D <datetime>] [- R & lt <Reference file or directory>] [- T <datetime>] [- Help ] [- Version ] [file or directory ...]

 

parameter:

• -a change in the reading file time records.
  • 

    [root@oldboy oldboy]# stat new.txt
      File: `new.txt'
      Size: 120             Blocks: 8          IO Block: 4096   regular file
    Device: 803h/2051d      Inode: 275539      Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2019-11-06 22:10:48.234818898 +0800
    Modify: 2019-11-07 18:48:17.389776861 +0800
    Change: 2019-11-07 18:48:17.390776816 +0800
    
    [root@oldboy oldboy]# touch new.txt -a
    
    # touch -a修改了atime和ctime
    [root@oldboy oldboy]# stat new.txt    
      File: `new.txt'
      Size: 120             Blocks: 8          IO Block: 4096   regular file
    Device: 803h/2051d      Inode: 275539      Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2019-11-07 19:49:23.350646538 +0800
    Modify: 2019-11-07 18:48:17.389776861 +0800
    Change: 2019-11-07 19:49:23.350646538 +0800

    touch -a effect

     

• -m change to modify file time records.
  • 

    [root@oldboy oldboy]# stat new.txt    
      File: `new.txt'
      Size: 120             Blocks: 8          IO Block: 4096   regular file
    Device: 803h/2051d      Inode: 275539      Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2019-11-07 19:49:23.350646538 +0800
    Modify: 2019-11-07 18:48:17.389776861 +0800
    Change: 2019-11-07 19:49:23.350646538 +0800
    
    [root@oldboy oldboy]# touch new.txt -m
    
    # touch -m 修改了mtime和ctime
    [root@oldboy oldboy]# stat new.txt 
      File: `new.txt'
      Size: 120             Blocks: 8          IO Block: 4096   regular file
    Device: 803h/2051d      Inode: 275539      Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Access: 2019-11-07 19:49:23.350646538 +0800
    Modify: 2019-11-07 19:51:19.971719215 +0800
    Change: 2019-11-07 19:51:19.971719215 +0800

    touch -m effect

     

• -c，--no-create 
  • do not create any files
  • If the purpose of the file does not exist, does not create a new file.
  • 

    [root@oldboy oldboy]# touch -c nn
    [root@oldboy oldboy]# ls nn
    ls: cannot access nn: No such file or directory

    touch -c Do not create file

     

• -f
  • ignored
  • Do not use, in order to retain compatibility with other unix systems.
• -r，--reference=FILE
  • use this file's times instead of current time
  • Recording a reference time profile, with the same effect --file.
• -d，--date=STRING
  • parse STRING and use it instead of current time
  • Set the time and date, you can use a variety of different formats.
• -t
  • use [[CC]YY]MMDDhhmm[.ss] instead of current time
  • File recording time set, date format instruction is the same.

 

Example:

1. Check the before and after results of touch file found modified atime, ctime and mtime, modify the time attributes of the file.

[root@oldboy oldboy]# stat name.txt
  File: `name.txt'
  Size: 35              Blocks: 8          IO Block: 4096   regular file
Device: 803h/2051d      Inode: 275549      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-11-07 19:46:37.014647959 +0800
Modify: 2019-11-07 19:46:37.014647959 +0800
Change: 2019-11-07 19:46:37.014647959 +0800

[root@oldboy oldboy]# touch name.txt

[root@oldboy oldboy]# stat name.txt 
  File: `name.txt'
  Size: 35              Blocks: 8          IO Block: 4096   regular file
Device: 803h/2051d      Inode: 275549      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-11-07 19:47:19.574647813 +0800
Modify: 2019-11-07 19:47:19.574647813 +0800
Change: 2019-11-07 19:47:19.574647813 +0800