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选题: 9 Useful touch command examples in Linux
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9 Useful touch command examples in Linux
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======
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Touch command is used to create empty files and also changes the timestamps of existing files on Unix & Linux System. Changing timestamps here means updating the access and modification time of files and directories.
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[![touch-command-examples-linux][1]![touch-command-examples-linux][2]][2]
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Let’s have a look on the syntax and options used in touch command,
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**Syntax** : # touch {options} {file}
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Options used in touch command,
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![touch-command-options][1]
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![touch-command-options][3]
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In this article we will walk through 9 useful touch command examples in Linux,
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### Example:1 Create an empty file using touch
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To create an empty file using touch command on Linux systems, type touch followed by the file name, example is shown below,
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```
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[root@linuxtechi ~]# touch devops.txt
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[root@linuxtechi ~]# ls -l devops.txt
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-rw-r--r--. 1 root root 0 Mar 29 22:39 devops.txt
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[root@linuxtechi ~]#
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```
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### Example:2 Create empty files in bulk using touch
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There can be some scenario where we have to create lots of empty files for some testing, this can be easily achieved using touch command,
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```
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[root@linuxtechi ~]# touch sysadm-{1..20}.txt
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```
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In the above example we have created 20 empty files with name sysadm-1.txt to sysadm-20.txt, you can change the name and numbers based on your requirements.
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### Example:3 Change / Update access time of a file and directory
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Let’s assume we want to change access time of a file called “ **devops.txt** “, to do this use ‘ **-a** ‘ option in touch command followed by file name, example is shown below,
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```
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[root@linuxtechi ~]# touch -a devops.txt
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[root@linuxtechi ~]#
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```
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Now verify whether access time of a file has been updated or not using ‘stat’ command
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```
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[root@linuxtechi ~]# stat devops.txt
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File: ‘devops.txt’
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Size: 0 Blocks: 0 IO Block: 4096 regular empty file
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Device: fd00h/64768d Inode: 67324178 Links: 1
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Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
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Context: unconfined_u:object_r:admin_home_t:s0
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Access: 2018-03-29 23:03:10.902000000 -0400
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Modify: 2018-03-29 22:39:29.365000000 -0400
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Change: 2018-03-29 23:03:10.902000000 -0400
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Birth: -
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[root@linuxtechi ~]#
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```
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**Change access time of a directory** ,
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Let’s assume we have a ‘nfsshare’ folder under /mnt, Let’s change the access time of this folder using the below command,
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```
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[root@linuxtechi ~]# touch -m /mnt/nfsshare/
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[root@linuxtechi ~]#
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[root@linuxtechi ~]# stat /mnt/nfsshare/
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File: ‘/mnt/nfsshare/’
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Size: 6 Blocks: 0 IO Block: 4096 directory
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Device: fd00h/64768d Inode: 2258 Links: 2
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Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
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Context: unconfined_u:object_r:mnt_t:s0
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Access: 2018-03-29 23:34:38.095000000 -0400
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Modify: 2018-03-03 10:42:45.194000000 -0500
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Change: 2018-03-29 23:34:38.095000000 -0400
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Birth: -
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[root@linuxtechi ~]#
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```
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### Example:4 Change Access time without creating new file
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There can be some situations where we want to change access time of a file if it exists and avoid creating the file. Using ‘ **-c** ‘ option in touch command, we can change access time of a file if it exists and will not a create a file, if it doesn’t exist.
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```
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[root@linuxtechi ~]# touch -c sysadm-20.txt
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[root@linuxtechi ~]# touch -c winadm-20.txt
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[root@linuxtechi ~]# ls -l winadm-20.txt
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ls: cannot access winadm-20.txt: No such file or directory
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[root@linuxtechi ~]#
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```
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### Example:5 Change Modification time of a file and directory
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Using ‘ **-m** ‘ option in touch command, we can change the modification time of a file and directory,
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Let’s change the modification time of a file called “devops.txt”,
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```
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[root@linuxtechi ~]# touch -m devops.txt
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[root@linuxtechi ~]#
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```
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Now verify whether modification time has been changed or not using stat command,
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```
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[root@linuxtechi ~]# stat devops.txt
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File: ‘devops.txt’
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Size: 0 Blocks: 0 IO Block: 4096 regular empty file
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Device: fd00h/64768d Inode: 67324178 Links: 1
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Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
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Context: unconfined_u:object_r:admin_home_t:s0
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Access: 2018-03-29 23:03:10.902000000 -0400
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Modify: 2018-03-29 23:59:49.106000000 -0400
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Change: 2018-03-29 23:59:49.106000000 -0400
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Birth: -
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[root@linuxtechi ~]#
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```
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Similarly, we can change modification time of a directory,
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```
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[root@linuxtechi ~]# touch -m /mnt/nfsshare/
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[root@linuxtechi ~]#
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```
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### Example:6 Changing access and modification time in one go
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Use “ **-am** ” option in touch command to change the access and modification together or in one go, example is shown below,
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```
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[root@linuxtechi ~]# touch -am devops.txt
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[root@linuxtechi ~]#
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```
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Cross verify the access and modification time using stat,
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```
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[root@linuxtechi ~]# stat devops.txt
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File: ‘devops.txt’
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Size: 0 Blocks: 0 IO Block: 4096 regular empty file
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Device: fd00h/64768d Inode: 67324178 Links: 1
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Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
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Context: unconfined_u:object_r:admin_home_t:s0
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Access: 2018-03-30 00:06:20.145000000 -0400
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Modify: 2018-03-30 00:06:20.145000000 -0400
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Change: 2018-03-30 00:06:20.145000000 -0400
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Birth: -
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[root@linuxtechi ~]#
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```
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### Example:7 Set the Access & modification time to a specific date and time
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Whenever we do change access and modification time of a file & directory using touch command, then it set the current time as access & modification time of that file or directory,
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Let’s assume we want to set specific date and time as access & modification time of a file, this is can be achieved using ‘-c’ & ‘-t’ option in touch command,
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Date and Time can be specified in the format: {CCYY}MMDDhhmm.ss
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Where:
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* CC – First two digits of a year
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* YY – Second two digits of a year
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* MM – Month of the Year (01-12)
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* DD – Day of the Month (01-31)
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* hh – Hour of the day (00-23)
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* mm – Minutes of the hour (00-59)
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Let’s set the access & modification time of devops.txt file for future date and time( 2025 year, 10th Month, 19th day of month, 18th hours and 20th minute)
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```
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[root@linuxtechi ~]# touch -c -t 202510191820 devops.txt
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```
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Use stat command to view the update access & modification time,
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![stat-command-output-linux][1]
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![stat-command-output-linux][4]
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Set the Access and Modification time based on date string, Use ‘-d’ option in touch command and then specify the date string followed by the file name, example is shown below,
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```
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[root@linuxtechi ~]# touch -c -d "2010-02-07 20:15:12.000000000 +0530" sysadm-29.txt
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[root@linuxtechi ~]#
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```
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Verify the status using stat command,
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```
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[root@linuxtechi ~]# stat sysadm-20.txt
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File: ‘sysadm-20.txt’
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Size: 0 Blocks: 0 IO Block: 4096 regular empty file
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Device: fd00h/64768d Inode: 67324189 Links: 1
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Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
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Context: unconfined_u:object_r:admin_home_t:s0
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Access: 2010-02-07 20:15:12.000000000 +0530
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Modify: 2010-02-07 20:15:12.000000000 +0530
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Change: 2018-03-30 10:23:31.584000000 +0530
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Birth: -
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[root@linuxtechi ~]#
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```
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**Note:** In above commands, if we don’t specify ‘-c’ then touch command will create a new file in case it doesn’t exist on the system and will set the timestamps whatever is mentioned in the command.
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### Example:8 Set the timestamps to a file using a reference file (-r)
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In touch command we can use a reference file for setting the timestamps of file or directory. Let’s assume I want to set the same timestamps of file “sysadm-20.txt” on “devops.txt” file. This can be easily achieved using ‘-r’ option in touch.
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**Syntax:** # touch -r {reference-file} actual-file
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```
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[root@linuxtechi ~]# touch -r sysadm-20.txt devops.txt
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[root@linuxtechi ~]#
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```
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### Example:9 Change Access & Modification time on symbolic link file
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By default, whenever we try to change timestamps of a symbolic link file using touch command then it will change the timestamps of original file only, In case you want to change timestamps of a symbolic link file then this can be achieved using ‘-h’ option in touch command,
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**Syntax:** # touch -h {symbolic link file}
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```
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[root@linuxtechi opt]# ls -l /root/linuxgeeks.txt
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lrwxrwxrwx. 1 root root 15 Mar 30 10:56 /root/linuxgeeks.txt -> linuxadmins.txt
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[root@linuxtechi ~]# touch -t 203010191820 -h linuxgeeks.txt
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[root@linuxtechi ~]# ls -l linuxgeeks.txt
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lrwxrwxrwx. 1 root root 15 Oct 19 2030 linuxgeeks.txt -> linuxadmins.txt
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[root@linuxtechi ~]#
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```
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That’s all from this tutorial, I hope these examples help you to understand touch command. Please do share your valuable feedback and comments.
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--------------------------------------------------------------------------------
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via: https://www.linuxtechi.com/9-useful-touch-command-examples-linux/
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作者：[Pradeep Kumar][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://www.linuxtechi.com/author/pradeep/
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[1]:https://www.linuxtechi.com/wp-content/plugins/lazy-load/images/1x1.trans.gif
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[2]:https://www.linuxtechi.com/wp-content/uploads/2018/03/touch-command-examples-linux.jpg
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[3]:https://www.linuxtechi.com/wp-content/uploads/2018/03/touch-command-options.jpg
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[4]:https://www.linuxtechi.com/wp-content/uploads/2018/03/stat-command-output-linux.jpg
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