How can I change the «last modified» (or «last changed») time of files on Linux?
I tried touch -t , but its precision is only one second: when I use stat , I see there are 9 digits all zero after the decimal ( . ):
Access: 2013-10-10 15:12:00.000000000 +0200 Modify: 2013-10-10 15:12:00.000000000 +0200 Change: 2015-11-22 18:39:54.369524868 +0100 How can I change the «last modify» and «last change» time of files to the precision of 9 numbers after the decimal point?
2 Answers 2
touch -m -d '2015-01-01 01:01:01.123456789' file.ext When you modify a file’s contents, both the mtime and ctime get updated. touch -m will alter both times. When you rename a file or change the permissions, only the ctime is updated.
@glennjackman I mean how to modify the last change time, the command @Patriceleversque gave is for modifying the last modify time only
Oh, I see. Interesting. When you specify a time, the mtime changes to that time and the ctime changes to the current time. Since the ctime really reflects the file’s inode, I guess the OS (or the filesystem) won’t let you set the ctime to a specified time.
The touch command allows you to alter the modification time and/or the access time. You cannot set the change time arbitrarily: that is set to the time when you alter either of the other two times.
The reason for this is that touch relies upon a system call which can do only the combinations noted above. The source-code (in GNU coreutils) uses this chunk:
ok = (fdutimensat (fd, AT_FDCWD, (fd == STDOUT_FILENO ? NULL : file), t, (no_dereference && fd == -1) ? AT_SYMLINK_NOFOLLOW : 0) == 0); which in turn (see source) calls futimens or utimensat . These functions are both POSIX, which notes
Upon completion, futimens() and utimensat() shall mark the last file status change timestamp for update.
The status change timestamp is what you cannot set arbitrarily.
The two POSIX functions accept timespec parameters, which provide resolution in nanoseconds. Your computer’s filesystem may or may not support that (though the result from stat indicates that it may).
The default POSIX-style -t option is as noted limited to 1-second resolution. However (still POSIX) the -d option provides for fractions of a second:
GNU coreutils supports this -d option, allowing nanosecond resolution. The documentation for touch gives as an example
--date="2004-02-27 14:19:13.489392193 +0530" (where —date is a long name equivalent to -d ).
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) "$" done Adjusting the date of images based on meta info in the image would be pretty useful. ImageMagick’s identify can be used. e.g. ‘identify -verbose
It’s been a long time since I wrote any kind of Unix program, but I accidentally set the year incorrectly on a bunch of Christmas photos, and I knew if I didn’t change the date from 2015 to 2014 it would be a problem later on.
Maybe, this is an easy task, but I didn’t find any simple way to do it.
I modified a script I found here, which originally was used to modify the date by minus one month.
Here’s the original script:
#!/bin/bash # find specific files files=$(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
Linux Change Modification date of files?
I extract .php files in one of my directory and there were many files in there so most of the files replaced ! but I have a problem since the modification date of new files are 23 April 2013 so I want to find all files and folders in this directory that are not 23 April 2013 ! In other way, I want to change all files in this directory that have 23 April 2013 modification date to 30/08/2013 ! How its possible to find and change the files ? Combine FIND and TOUCH function to replace all files modification date.
1 Answer 1
You could cd to the folder containing the PHP files and:
touch -d '30 August 2013' *.php Or if it has sub folders with php files — search through them recursively:
find /path/to/your/php/ -exec touch -d '30 August 2013' *.php <> \; the folder ‘php’ in the command above would be included.
If you ONLY need to find/change EXACTLY files modified on 23 April 2013, you can use the -mtime parameter in your find command.
- -mtime +60 means you are looking for a file modified 60 days ago or more.
- -mtime -60 means less than 60 days.
- -mtime 60 If you skip + or — it means exactly 60 days.
So modifying the command above like this:
find /path/to/your/php/ -mtime 127 -exec touch -d '30 August 2013' *.php <> \; Where 127 is the exact amount of days since 23 April (if my quick head calculation is correct). Else you can change the number to the correct amount of days, or use the + or — as described above if it doesn’t need to be ‘that’ exact.
You can read more about the find commands -mtime parameter here: http://www.cyberciti.biz/faq/howto-finding-files-by-date/
(yes I borrowed 3 lines from there)