Linux set file times

How can I change the date modified/created of a file?

Is there a way to change the date when a file was modified/created (which is shown in Nautilus or with the ls -l command)? Ideally I am looking for a command which can change the date/time stamps of a whole bunch of files to a certain amount of time earlier or later (e.g. +8 hours or -4 days etc.).

6 Answers 6

As long as you are the owner of the file (or root), you can change the modification time of a file using the touch command:

By default this will set the file’s modification time to the current time, but there are a number of flags, such as the -d flag to pick a particular date. So for example, to set a file as being modified two hours before the present, you could use the following:

touch -d "2 hours ago" filename 

If you want to modify the file relative to its existing modification time instead, the following should do the trick:

touch -d "$(date -R -r filename) - 2 hours" filename 

If you want to modify a large number of files, you could use the following:

find DIRECTORY -print | while read filename; do # do whatever you want with the file touch -d "$(date -R -r "$filename") - 2 hours" "$filename" done 

You can change the arguments to find to select only the files you are interested in. If you only want to update the file modification times relative to the present time, you can simplify this to:

find DIRECTORY -exec touch -d "2 hours ago" <> + 

This form isn’t possible with the file time relative version because it uses the shell to form the arguments to touch .

As far as the creation time goes, most Linux file systems do not keep track of this value. There is a ctime associated with files, but it tracks when the file metadata was last changed. If the file never has its permissions changed, it might happen to hold the creation time, but this is a coincidence. Explicitly changing the file modification time counts as a metadata change, so will also have the side effect of updating the ctime .

To mention the simpler case when all files are in the same folder: touch -d «2 hours ago» /path/*.txt , for example.

The information about ctime as a metadata change time is from POSIX. I don’t know if the shell fragments in my answer would work with strict POSIX shell utilities. But they definitely work on Ubuntu, which is the context for answers on this site.

Easiest way — accessed and modified will be the same:

touch -a -m -t 201512180130.09 fileName.ext 

-a = accessed -m = modified -t = timestamp - use [[CC]YY]MMDDhhmm[.ss] time format 

If you wish to use NOW just drop the -t and the timestamp.

To verify they are all the same: stat fileName.ext

I tried to verify it using stat, but neither of the touch flags lead to a correct result. Modification date is adjusted, but changed and accessed date are actually changed to NOW

@ljoseph, take a look here: https://www.howtogeek.com/517098/linux-file-timestamps-explained-atime-mtime-and-ctime/#:~:text=%E2%80%9CModified%E2%80%9D%20means%20something%20inside%20the,will%20update%20the%20changed%20timestamp.

Using «-a» and «-m» together is probably unnecessary, «-a» is «change only the access time», and «-m» is «change only the modification time». If you want to update both, you don’t need to use any option.

Thanks for the help. This worked for me:

In the terminal go to the directory for date-edit. Then type:

find -print | while read filename; do # do whatever you want with the file touch -t 201203101513 "$filename" done 

You wil see a «>» after you hit enter, exept for the last time -> «done».

Note: You may want to change «201203101513»

«201203101513» = is the date you want for all the files in this directory.

Webpage is no longer, albeit it is 6 years later. Nonetheless, this is the answer I was looking for. For those who want to include seconds in their time, use .ss where ss is the number of seconds. (Note: this does not seem to control sub-second timings such as nanoseconds or milliseconds, which for me just appeared as zeros; however, this difference was permissible for my use-case.)

Touch can reference a file’s date all by itself, no need to call date or use command substitution. Here’s a bit from touch’s info page:

`-r FILE' `--reference=FILE' Use the times of the reference FILE instead of the current time. If this option is combined with the `--date=TIME' (`-d TIME') option, the reference FILE's time is the origin for any relative TIMEs given, but is otherwise ignored. For example, `-r foo -d '-5 seconds'' specifies a time stamp equal to five seconds before the corresponding time stamp for `foo'. If FILE is a symbolic link, the reference timestamp is taken from the target of the symlink, unless `-h' was also in effect. 

For example, to add 8 hours to a file’s date (filename of file quoted just in case of spaces, etc):

touch -r "file" -d '+8 hour' "file" 

Using a loop over all files in the current dir:

for i in *; do touch -r "$i" -d '+8 hour' "$i"; done 

I’ve heard that using a * and letting for pick the filenames itself is safer, but using find -print0 | xargs -0 touch . should handle most crazy characters like newlines, spaces, quotes, backslashes in a filename. (PS. try not to use crazy characters in filenames in the first place).

For example, to find all files in thatdir whose filenames start with an s , and add one day to those file’s modified timestamp, use:

find thatdir -name "s*" -print0 | xargs -0 -I '<>' touch -r '<>' -d '+1 day' '<>' 

This little script at least works for me:

#!/bin/bash # find specific files files=$(find . -type f -name '*.JPG') # use newline as file separator (handle spaces in filenames) IFS=$'\n' for f in $ do # read file modification date using stat as seconds # adjust date backwards (1 month) using date and print in correct format # change file time using touch touch -t $(date -v -1m -r $(stat -f %m "$") +%Y%m%d%H%M.%S) "$" done 

Adjusting the date of images based on meta info in the image would be pretty useful. ImageMagick’s identify can be used. e.g. ‘identify -verbose |grep -i date’, ‘identify -format %[exif:DateTime] ‘ might show ‘2015:01:08 10:19:10’ (not all images have exif data). This works(using sed to convert date to format touch can handle): ‘touch -d $(identify -format %[exif:DateTime] $f|sed -r ‘s/:/-/;s/:/-/;’) $f’

It’s been a long time since I wrote any kind of Unix program, but I accidentally set the year incorrectly on a bunch of Christmas photos, and I knew if I didn’t change the date from 2015 to 2014 it would be a problem later on.

Maybe, this is an easy task, but I didn’t find any simple way to do it.

I modified a script I found here, which originally was used to modify the date by minus one month.

Here’s the original script:

#!/bin/bash # find specific files files=$(find . -type f -name '*.JPG') # use newline as file separator (handle spaces in filenames) IFS=$'\n' for f in $ do # read file modification date using stat as seconds # adjust date backwards (1 month) using date and print in correct format # change file time using touch touch -t $(date -v -1m -r $(stat -f %m "$") +%Y%m%d%H%M.%S) "$" done 

Here’s my modified script that forced the date to the year «2014»:

#!/bin/bash # find specific files #files=$(find . -type f -name '*.JPG') # use newline as file separator (handle spaces in filenames) IFS=$'\n' for f in $* do # read file modification date using stat as seconds # adjust date backwards (1 month) using date and print in correct format # change file time using touch touch -t $(date -v +1y -r $(stat -f %m "$") +2014%m%d%H%M.%S) "$" done 

I now realize I could have done a more generic version:

#!/bin/bash # find specific files #files=$(find . -type f -name '*.JPG') # use newline as file separator (handle spaces in filenames) IFS=$'\n' for f in $* do # read file modification date using stat as seconds # adjust date backwards (1 month) using date and print in correct format # change file time using touch (+1y adds a year "-1y" subtracts a year) # Below line subtracts a year touch -t $(date -v -1y -r $(stat -f %m "$") +%Y%m%d%H%M.%S) "$" # Below line adds a year # touch -t $(date -v +1y -r $(stat -f %m "$") +%Y%m%d%H%M.%S) "$" done 

To use this file you would need to write it and

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Linux Touch Command

The touch command allows us to update the timestamps on existing files and directories as well as creating new, empty files.

In this guide, we will show you how to use the touch command through practical examples and detailed explanations of the most common command options.

Linux Files Timestamps #

Before going into how to use the touch command, let’s start by reviewing the file timestamps in Linux.

A file in Linux has three timestamps:

• atime (access time) — The last time the file was accessed/opened by some command or application such as cat , vim or grep .
• mtime (modify time) — The last time the file’s content was modified.
• ctime (change time) — The last time the file’s attribute or content was changed. The attribute includes file permissions, file ownership or file location.

To display the file status including the timestamps, use the stat command.

Creating a new file requires write permissions on the parent directory. Otherwise, you will receive a permission denied error.

How to Use the touch Command #

In it’s simplest form when used without any options, if the file name specified as an argument doesn’t exist touch will create a new file.

If the file already exists touch will change the file last access and modification times to the current time.

For example, if the file file1 doesn’t exist the following command will create it otherwise, it will change its timestamps:

To create or modify multiple files at once, specify the file names as arguments:

If you don’t want the touch command to create new files, use the -c ( —no-create ) option.

For example, if the file file1 exist the following command will change the file timestamps otherwise, it will do nothing:

Changing only access or modification times #

By default, if no option is used touch will update the file last access and modification times to the current time. By using the -a and -m options, you can change only one of these timestamps.

Change only the access time #

Use the -a option to change only the file’s access time:

Change only the modify time #

Use the -m option to change the file’s modify time:

When changing the modify time, the change time will be also updated.

Setting specific timestamps #

The touch command also allows us to update or create a file with a specific time other than the current time.

Use the -d ( —date= ) option to specify a date string and use it instead of the current time.

For example, to change both the last access and modification times of file1 to 1 June 2018 11:02 you would use the following command:

touch -d '1 June 2018 11:02' file1

The date string needs to be enclosed in single quotes.

You can also provide a partial date-time string to the touch command. Providing only the date, automatically changes the year to the current one:

Use the -t option to specify a timestamp and use it instead of the current time. The timestamp argument needs to be in the following format:

For example, the following command will set the last access and modification times of file1 to 1 June 11:02 of the current year.

Using the timestamp of another file #

The -r ( —reference= ) option allow us to specify a reference file and use its timestamps instead of the current time.

For example, the following command will tell touch to use the times of file1 for file2 :

Changing symbolic link timestamp #

By default, if you use a touch command on a symbolic link it will change the timestamps of its referenced file.

Use the -h ( —no-dereference ) to modify the timestamp of the symlink.

For example, to change the timestamps of the symbolic link symlink1 you would use:

Conclusion #

By now you should have a good understanding of how to use the Linux touch command.

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