touch (修改文件時間戳)

rose1 發表于 2020-07-29 17:04

瀏覽次數：

命令行 Unix&Linux命令 touch

在手機上閱讀

釋放雙眼，帶上耳機，聽聽看~！

00:00

在類似Unix的操作系統上，touch命令會修改文件時間戳。如果該文件不存在，則會創建一個具有該名稱的空文件。本文檔介紹了GNU / Linux touch版本。

查看英文版

1 touch 運行系統環境

2 touch 說明

3 touch 語法

4 touch 例子

touch 運行系統環境

Linux

touch 說明

時間戳是與文件相關聯的信息，用于標識文件歷史記錄中的重要時間。一個文件可以具有多個時間戳，可以通過手動設置其中一些來“偽造”它們。在內部，操作系統將這些時間存儲為自稱為epoch的任意日期以來經過的時間。對于類似Unix的操作系統，紀元為1970 年1月1日（星期四）00:00:00協調世界時（UTC）。

在Linux中，與文件關聯的三個時間戳記：

時間戳類型	描述	縮寫
訪問時間	上次讀取文件的時間。	atime
修改時間	上次修改文件內容的時間。	mtime
變更時間	上次更改文件的元數據（稱為狀態）。狀態信息包括文件的權限及其時間戳。每次文件發生任何事情，其狀態至少都會改變一個元素，并且其ctime會設置為當前系統時間。	ctime

atime和mtime是文件狀態元數據的一部分。因此，當您更改文件的atime（-a）或mtime（-m）時，其ctime會自動設置為當前時間。

無法手動設置ctime。

如果用戶擁有文件，則可以將文件的atime或mtime設置為將來或過去。

A timestamp is information associated with a file that identifies an important time in the file's history. A file can have multiple timestamps, and some of them can be "forged" by setting them manually. Internally, the operating system stores these times as time elapsed since an arbitrary date called the epoch. For Unix like operating systems, the epoch is 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970.

In Linux, there are three timestamps associated with a file:

Timestamp type	Description	Abbreviation
Access time	The last time the file was read.	atime
Modification time	The last time the contents of the file were modified.	mtime
Change time	The last time the file's metadata, called the Status, was changed. Status information includes a file's permissions and its timestamps. Every time anything happens to a file, at least one element of its status changes, and its ctime is set to the current system time.	ctime

The atime and mtime are part of a file's status metadata. Therefore, when you change the atime (-a) or mtime (-m) of a file, its ctime is automatically set to the current time.

There is no way to manually set the ctime.

A file's atime or mtime can be set to the future or the past if the user owns the file.

查看英文版

touch 語法

touch [[-a] [-m] | [--time=timetype] [...]] [[-d datestring] | [-t timestamp]]
      [-c] [-f] [-h] [-r reffile] file [file ...]

touch --version

touch --help

唯一需要的參數，以觸摸為一個文件名：

文件	時間應更改的文件。如果文件不存在，除非使用-c或-h選項，否則將創建該文件。可以將多個文件指定為file0 file1 file2 ...等。（如果文件是破折號“ - ”，請觸摸以修改特殊文件描述符標準輸出。請參見示例。）

如果沒有任何選項，touch會將文件的atime，mtime和ctime 更改為當前系統時間。

選件

選項

描述

-a

僅設置訪問時間。

-c,
--no-create

不要創建文件。

-d datestring,
--date=datestring

解析日期字符串 datestring，并使用它代替當前時間。-d選項接受對date命令有效的字符串。

參見示例。

除了具有寫訪問權之外，用戶還必須擁有文件才能將其時間設置為過去或將來。

-f

該選項不執行任何操作，但可以接受以提供與BSD版本的touch的兼容性。

-h,
--no-dereference

如果file是符號鏈接，并且指定了此選項，那么touch將修改符號鏈接的時間戳，而不是其引用文件的時間戳。如果未指定此選項，則在進行修改之前，touch將取消引用符號鏈接。

此選項表示-c：如果文件不存在，則不會創建任何內容。

-m

僅設置修改時間。

-r=reffile,
--reference=reffile

將文件時間設置為文件reffile的時間，而不是當前時間。

除了具有寫訪問權之外，用戶還必須擁有文件才能將其時間設置為過去或將來。

-t timestamp

使用數字時間戳而不是當前時間。時間戳的格式為[[ CC ] YY ] MMDDhhmm [ .ss ]。

參見示例。

除了具有寫訪問權之外，用戶還必須擁有文件才能將其時間設置為過去或將來。

--time=timetype

指定設置時間類型的另一種方法（與-a和-m一樣）。timetype

值必須是以下之一：

atime, access, use	設置訪問時間。等效于-a。
mtime, modify	設置修改時間。等效于-m。

可以無損地指定兩次該選項。例如，-- time = atime --time = mtime與-am相同。

--help

顯示幫助消息，然后退出。

--version

顯示版本信息，然后退出。

筆記

該-d選項接受一個人類可讀的日期字符串。例如，“ 7月4日”，“ 7月4日”，“ 0:00”或“ 7月4日00:00:00”。如果省略年，月或日，則使用當前系統時間值。如果省略時間，則使用午夜。可以在字符串中的月份之前或之后指定日期。根據喜好，一位數字可以加零或不加零。如果指定秒，它們是在由結腸的時間的前面（：）。

-t采用數字時間戳，該時間戳將月份，日期，小時和分鐘表示為MMDDHHMM。例如，07040000將在7月4日午夜。世紀，年和秒是可選的，可以指定為CCYYMMDDHHMM.SS。如果指定了秒數，則必須在它們前面加上句點（。）。

可以指定將來的時間。例如，-d“ Jan 1 2029”。除了具有寫訪問權之外，用戶還必須擁有文件才能將其時間設置為過去或將來。

由于無法手動設置ctimes，因此-r，-d和-t選項只能修改atimes和mtimes。觸摸文件時，ctime將始終設置為當前系統時間。

時區

如果設置了環境變量 TZ的值，則所有操作都將使用該時區。否則，將使用系統默認時區。

要設置TZ環境變量，請使用命令tzselect。

退出狀態

如果所有操作成功，觸摸的退出狀態為零。任何非零值表示失敗。

touch [[-a] [-m] | [--time=timetype] [...]] [[-d datestring] | [-t timestamp]]
      [-c] [-f] [-h] [-r reffile] file [file ...]

touch --version

touch --help

The only required argument to touch is a file name:

file	A file whose times should be changed. If file does not exist, it is created, unless the -c or -h options are used. Multiple files may be specified as file0 file1 file2... etc. (If file is a dash "-", touch modifies the special file descriptor standard output. See examples.)

With no options, touch will change the atime, mtime, and ctime of file to the current system time.

Options

Option

Description

-a

Set the access time only.

-c,
--no-create

Do not create files.

-d datestring,
--date=datestring

Parse the date string datestring, and use it instead of current time. Strings valid to the date command are accepted by the -d option.

See Examples.

In addition to having write access, the user must also own a file to set its times to the past or future.

-f

This option does nothing, but is accepted to provide compatibility with BSD versions of touch.

-h,
--no-dereference

If file is a symbolic link and this option is specified, touch will modify the timestamp of the symlink, rather than its referenced file. If this option is not specified, touch will dereference symlinks before making modifications.

This option implies -c: nothing is created if file does not exist.

-m

Set modification time only.

-r=reffile,
--reference=reffile

Set the times of file to the times of file reffile instead of the current time.

In addition to having write access, the user must also own a file to set its times to the past or future.

-t timestamp

Use the numeric timestamp instead of the current time. The format of timestamp is [[CC]YY]MMDDhhmm[.ss].

See Examples.

In addition to having write access, the user must also own a file to set its times to the past or future.

--time=timetype

An alternate way to specify what type of time to set (as with -a and -m).

The value of timetype must be one of the following:

atime, access, use	Set access time. Equivalent to -a.
mtime, modify	Set modification time. Equivalent to -m.

This option can be specified twice nondestructively. For example, --time=atime --time=mtime is the same as -am.

--help

Display a help message, and exit.

--version

Display version information, and exit.

Notes

The -d option takes a human-readable date string. For example, "July 4", "4 Jul", "0:00", or "Jul 4 2017 00:00:00". If year, month, or day are omitted, the current system time values are used. If the time is omitted, midnight is used. The day may be specified before or after the month in the string. Single digit numbers may be prefixed with a zero, or not, according to preference. If seconds are specified, they are to be preceded in the time by a colon ( : ).

-t takes a numeric timestamp, which expresses the month, date, hour, and minute as MMDDHHMM. For example, 07040000 would be midnight on the fourth of July. Century, years, and seconds are optional, and may be specified as CCYYMMDDHHMM.SS. If seconds are specified, they are to be preceded with a period ( . ).

Specifying times in the future is okay. For example, -d "Jan 1 2029". In addition to having write access, the user must also own a file to set its times to the past or future.

Because there is no way to manually set ctimes, the -r, -d, and -t options can modify only atimes and mtimes. When a file is touched, the ctime will always be set to the current system time.

Time zones

If the value of environment variable TZ is set, all operations will use that time zone. Otherwise, the system default time zone is used.

To set the TZ environment variable, use the command tzselect.

Exit status

The exit status of touch is zero if all operations were successful. Any nonzero value indicates failure.

查看英文版

touch 例子

touch file.txt

如果存在file.txt，請將其訪問，修改和更改時間（atime，mtime和ctime）設置為當前系統時間。如果file.txt不存在，請使用該名稱創建一個空文件。

touch -c file.txt

如果存在file.txt，請將其時間設置為當前系統時間。如果不存在，則什么也不做。

touch -a file.txt

更改file.txt的時間。mtime不變。ctime設置為當前系統時間。如果file.txt不存在，則會創建它。

touch -h mysym

更改文件mysym的時間。如果是符號鏈接，請更改符號鏈接的時間，而不是引用文件的時間。

touch -cr a.txt b.txt

更改b.txt的訪問和修改時間以匹配a.txt的時間。ctime將被設置為當前系統時間。如果file.txt不存在，將不會創建。

touch -ahmcr a.txt b.txt

更改b.txt的atime和mtime 以匹配a.txt的atime和mtime 。如果file1.txt不存在，則不執行任何操作。如果b.txt是符號鏈接，請設置符號鏈接的時間。不要觸摸引用的文件。

touch --time=atime --no-dereference --time=mtime --no-create --reference=a.txt b.txt

與上一個命令相同。

touch -d "October 31" - > boo.txt

將標準輸出的atime和mtime設置為當年10月31日午夜。將標準輸出重定向（>）到boo.txt。

touch不能覆蓋現有文件的內容，但重定向會。如果boot.txt不存在，將創建它。如果存在boot.txt，它將被覆蓋。

touch -t "10310000" - > boo.txt

與上一個命令相同。

例子

touch -d "1 Feb" file1.txt

將file1.txt的atime和mtime設置為當年的2月1日。ctime設置為當前系統時間。

touch -d "February 1" file1.txt

與上一個命令相同。

touch --date="1 February" file1.txt

與上一個命令相同。

touch -d "01:02" file1.txt

今天將file1.txt的atime和mtime設置為1:02 AM。

touch -d "1:2" file1.txt

與上一個命令相同。

touch -md "Sep 1 1927 23:58:59" file1.txt

將file1.txt的mtime設置為1927年9月1日下午11:58和59秒。ctime設置為當前系統時間。時間沒有改變。

例子

touch --time=01020304 file1.txt

將file1.txt的atime和mtime設置為當年的1月2日，凌晨3:04。ctime設置為當前系統時間。

touch -t 01020304 file1.txt

與上一個命令相同。

touch -t 5006070405 file1.txt

將file1.txt的atime和mtime設置為2050年6月7日上午4:05。ctime設置為當前系統時間。

touch -t 205007080405 file1.txt

與上一個命令相同，但是明確指定了世紀（20）。

touch -at 195003040506.59 file1.txt

將file1.txt的時間設置為1950年3月4日，5：06 AM和59秒。ctime設置為當前系統時間。mtime不變。

使用統計信息檢查文件時間

您可以使用stat命令檢查文件的時間：

stat file.txt

stat：不能stat'file.txt'：沒有這樣的文件或目錄

touch file.txt; stat file.txt

  文件：'file.txt' 
  大小： 0           Blocks: 0          IO Block: 4096   常規空文件
設備： 802h/2050d  索引節點: 668116      鏈接: 1
訪問： (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
訪問： 2017-10-25 21:35:17.368254343 -0400
修改： 2017-10-25 21:35:17.368254343 -0400
更改： 2017-10-25 21:35:17.368254343 -0400
 Birth: -

touch -ad "July 12 1895" file.txt; stat file.txt

  文件：'file.txt' 
  大小： 0           Blocks: 0          IO Block: 4096   常規空文件
設備： 802h/2050d  索引節點: 668116      鏈接: 1
訪問： (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
訪問： 1895-07-12 00:00:00.000000000 -0500
修改： 2017-10-25 21:35:17.368254343 -0400
更改： 2017-10-25 21:35:55.487636366 -0400
 Birth: -

touch -mt 198307010000 file.txt; stat file.txt

  文件：'file.txt' 
  大小： 0           Blocks: 0          IO Block: 4096   常規空文件
設備: 802h/2050d  索引節點: 668116      鏈接: 1
訪問: (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
訪問: 1895-07-12 00:00:00.000000000 -0500
修改: 1983-07-01 00:00:00.000000000 -0400
Change: 2017-10-25 21:36:59.654589018 -0400
 Birth: -

for formatspec in 'file name:\t%n' 'accessed:\t%x' 'modified:\t%y' 'changed:\t%z'; do stat --printf="$formatspec\n" file.txt; done

文件名：file.txt 
訪問：   1895-07-12 00:00:00.000000000 -0500
修改：   1983-07-01 00:00:00.000000000 -0400
更改:    2017-10-25 21:36:59.654589018 -0400

注意：您可能會在這組示例中注意到，當atime更改為1895年7月12日時，時區也發生了變化。這是因為直到1918年4月1日，北美才頒布了夏令時（DST）。

touch file.txt

If file.txt exists, set its access, modification, and change times (atime, mtime, and ctime) to the current system time. If file.txt doesn't exist, create an empty file with that name.

touch -c file.txt

If file.txt exists, set its times to the current system time. If it does not exist, do nothing.

touch -a file.txt

Change the atime of file.txt. The mtime is not changed. The ctime is set to the current system time. If file.txt does not exist, it is created.

touch -h mysym

Change the times of file mysym. If it's a symbolic link, change the times of the symlink, not the times of the referenced file.

touch -cr a.txt b.txt

Change the access and modification times of b.txt to match the times of a.txt. The ctime will be set to the current system time. If file.txt does not exist, it will not be created.

touch -ahmcr a.txt b.txt

Change the atime and mtime of b.txt to match the atime and mtime of a.txt. If file1.txt doesn't exist, do nothing. If b.txt is a symlink, set the times of the symlink. Do not touch the referenced file.

touch --time=atime --no-dereference --time=mtime --no-create --reference=a.txt b.txt

Same as the previous command.

touch -d "October 31" - > boo.txt

Set the atime and mtime of standard output to midnight, October 31 of the current year. Redirect (>) standard output to boo.txt.

touch cannot overwrite the contents of an existing file, but the redirect will. If boot.txt does not exist, it will be created. If boot.txt exists, it will be overwritten.

touch -t "10310000" - > boo.txt

Same as the previous command.

Examples

touch -d "1 Feb" file1.txt

Set the atime and mtime of file1.txt to February 1st of the current year. The ctime is set to the current system time.

touch -d "February 1" file1.txt

Same as the previous command.

touch --date="1 February" file1.txt

Same as the previous command.

touch -d "01:02" file1.txt

Set the atime and mtime of file1.txt to 1:02 AM, today.

touch -d "1:2" file1.txt

Same as the previous command.

touch -md "Sep 1 1927 23:58:59" file1.txt

Set the mtime of file1.txt to September 1, 1927, 11:58 PM and 59 seconds. The ctime is set to the current system time. The atime is not changed.

Examples

touch --time=01020304 file1.txt

Set the atime and mtime of file1.txt to January 2, 3:04 AM of the current year. The ctime is set to the current system time.

touch -t 01020304 file1.txt

Same as the previous command.

touch -t 5006070405 file1.txt

Set the atime and mtime of file1.txt to June 7, 2050, 4:05 AM. The ctime is set to the current system time.

touch -t 205007080405 file1.txt

Same as the previous command, but explicitly specifying the century (20).

touch -at 195003040506.59 file1.txt

Set the atime of file1.txt to March 4, 1950, 5:06 AM and 59 seconds. The ctime is set to the current system time. The mtime is not changed.

Checking file times with stat

You can check the times of a file using the stat command:

stat file.txt

stat: cannot stat 'file.txt': No such file or directory

touch file.txt; stat file.txt

  File: 'file.txt'
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: 802h/2050d  Inode: 668116      Links: 1
Access: (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
Access: 2017-10-25 21:35:17.368254343 -0400
Modify: 2017-10-25 21:35:17.368254343 -0400
Change: 2017-10-25 21:35:17.368254343 -0400
 Birth: -

touch -ad "July 12 1895" file.txt; stat file.txt

  File: 'file.txt'
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: 802h/2050d  Inode: 668116      Links: 1
Access: (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
Access: 1895-07-12 00:00:00.000000000 -0500
Modify: 2017-10-25 21:35:17.368254343 -0400
Change: 2017-10-25 21:35:55.487636366 -0400
 Birth: -

touch -mt 198307010000 file.txt; stat file.txt

  File: 'file.txt'
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: 802h/2050d  Inode: 668116      Links: 1
Access: (0664/-rw-rw-r--)  Uid: ( 1001/    hope)   Gid: ( 1002/    hope)
Access: 1895-07-12 00:00:00.000000000 -0500
Modify: 1983-07-01 00:00:00.000000000 -0400
Change: 2017-10-25 21:36:59.654589018 -0400
 Birth: -

for formatspec in 'file name:\t%n' 'accessed:\t%x' 'modified:\t%y' 'changed:\t%z'; do stat --printf="$formatspec\n" file.txt; done

file name:  file.txt
accessed:   1895-07-12 00:00:00.000000000 -0500
modified:   1983-07-01 00:00:00.000000000 -0400
changed:    2017-10-25 21:36:59.654589018 -0400

Note: You may notice in this set of examples that when the atime was changed to July 12, 1895, the time zone changed. That's because Daylight Savings Time (DST) was not enacted in North America until April 1, 1918.

查看英文版

其他命令行

如此好文，分享給朋友