timestamp is used for questions that are about data specifying seconds since the epoch (19700101T00:00:00) or possible some other standard, and also for (date) and time information in filenames.

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74
votes
15answers
15k views

What are the legitimate uses of the `touch` command?

What's the point of the touch command? I know I can create empty files with it, but so is also the case with echo -n. Otherwise, why would someone need to change the timestamps of a file? Unless to ...
65
votes
3answers
220k views

Get file created/creation time? [duplicate]

Possible Duplicate: How do I do a ls and then sort the results by date created? Is there a command in Linux which displays when the file was created ? I see that ls -l gives the last modified ...
55
votes
7answers
122k views

How to find creation date of file?

I want to find out the creation date of particular file, not modification date or access date. I have tried with ls -ltrh and stat filename.
52
votes
2answers
20k views

Prepending a timestamp to each line of output from a command

I wish to prepend a timestamp to each line of output from a command. For example: foo bar baz would become [2011-12-13 12:20:38] foo [2011-12-13 12:21:32] bar [2011-12-13 12:22:20] baz ...where ...
50
votes
3answers
70k views

How do I do a ls and then sort the results by date created?

In what order are the dated ordered by? Certainly not alphanumeric order. ls -lt sorts by modification time. But I need creation time.
33
votes
7answers
176k views

Why does find -mtime +1 only return files older than 2 days?

I'm struggling to wrap my mind around why the find interprets file modification times the way it does. Specifically, I don't understand why the -mtime +1 doesn't show files less than 48 hours old. ...
27
votes
5answers
24k views

How to list files that were changed in a certain range of time?

How can I list recursively all files that were changed between 22.12.2011 and 24.12.2011?
23
votes
6answers
18k views

How can I do a “copy if changed” operation?

I would like to copy a set of files from directory A to directory B, with the caveat that if a file in directory A is identical to a file in directory B, that file should not be copied (and thus its ...
19
votes
3answers
3k views

How does touch -t work internally?

How does touch -t command works exactly, internally (I tried to find its source code but couldn't)?
19
votes
4answers
2k views

Finding command execution time in hindsight

I've just executed a long-running process from the bash prompt. In hindsight, I wish I'd run time on it, or noted down the time at which I kicked it off. Is there any way of getting this information ...
18
votes
3answers
50k views

Delete files older than X days +

I have found the command to delete files older than 5 days in a folder find /path/to/files* -mtime +5 -exec rm {} \; But how do I also do this for subdirectories in that folder?
18
votes
2answers
3k views

How long is the password for executing a command with sudo cached?

If I run a command which requires root privileges with sudo, I will be asked to enter the current user's password. After that for a while, if I execute the same sort of commands with sudo, I won't be ...
17
votes
6answers
13k views

Correlating /var/log/* timestamps

/var/log/messages, /var/log/syslog, and some other log files use a timestamp which contains an absolute time, like Jan 13 14:13:10. /var/log/Xorg.0.log and /var/log/dmesg, as well as the output of $ ...
16
votes
4answers
34k views

How to get milliseconds since Unix epoch?

I want to do a bash script that measures the launch time of a browser for that I am using an html which gets the time-stamp on-load in milliseconds using JavaScript. In the shell script just before i ...
16
votes
3answers
6k views

What file systems on Linux store the creation time?

Are there any (good known, reliable) file systems on Linux that store the creation time of files and directories in the i-node table? If there are, is the "changed" time replaced by the creation ...
15
votes
4answers
7k views

Changing the timestamp of a symlink

I know how to change the timestamp of a regular file: touch -t 201301291810 myfile.txt I was not able to do the same with a symlink. Is it possible? Distro: RHEL 5.8
13
votes
2answers
49k views

Cron job to delete files older than 3 days

I need to remove files older than 3 days with a cron job in 3 different directories. (these 3 directories are children of a parent directory /a/b/c/1 & /a/b/c/2 & /a/b/c/3) Can this be done ...
13
votes
4answers
5k views

Preserve modified time stamp after edit

For files within a specific folder, I would like vim to never touch "modified" timestamp at all. The background is that I use Bloxsom for blogging, which uses plain text files in ~/bloxsom as source ...
12
votes
3answers
2k views

How do I get the current time in a different time zone without changing system time? [duplicate]

I am trying to use 'date' to get the time in a different time zone, and failing. All the methods I've found on google involve changing the time zone on the system, but that is not what I want. Is ...
11
votes
5answers
729 views

Test if File was Modified After Date in File Name

I have a files named with YYYYMMDD in the file name, such as file-name-20151002.txt I want to determine if this file was modified after 2015-10-02. Notes: I can do this by looking at the output ...
10
votes
6answers
14k views

Shell script for moving oldest files?

How do I write a script for moving just the 20 oldest files from one folder to another? Is there a way to grab the oldest files in a folder?
10
votes
5answers
76k views

Display time stamp in dd/mm/yyyy_hh:mm:ss:ms in Unix or Linux

I need help to display date and time in desired format in Unix/ Linux. My desired format is: dd/mm/yyyy hh:mm:ss:ms in Unix or Linux. I got close using the following command: echo $(date +%x_%r) ...
9
votes
4answers
12k views

How do I change folder timestamps recursively to the newest file?

I was wondering if anyone knows how to change the timestamps of folders recursively based on the latest timestamp found of the files in that folder. So for example: jon@UbuntuPanther:/media/media/...
9
votes
2answers
3k views

What counts as a file modification or change?

Does renaming affect the file modify or access time? Is there a list somewhere of what changes which times?
8
votes
7answers
12k views

timestamp before an echo

Exists a nicer way to create timestamp in front of an echo? Currently I do it this way: #!/bin/sh if mount | grep -q /mnt/usb; then echo `date +%R\ ` "usb device already mounted" else ...
8
votes
2answers
6k views

Why does Unix store timestamps in a signed integer?

Why is a signed integer used to represent timestamps? There is a clearly defined start at 1970 that's represented as 0, so why would we need numbers before that? Are negative timestamps used anywhere?
8
votes
2answers
10k views

How to find difference between two timestamps up to milliseconds?

I am new to shell scripting. The heart of my script is to find the difference between two timestamps up to milliseconds. With me I have a file with content of timestamps only as 2012-09-13 15:00:29,...
7
votes
3answers
12k views

How can I change 'change' date of file?

How can I change 'change' date? $ touch -t 9901010000 test;stat test File: `test' Size: 0 Blocks: 0 IO Block: 4096 regular empty file Device: fe01h/65025d Inode: 11279017 ...
7
votes
2answers
1k views

Sort files by modification time

I've seen many questions and answers here using a construction along the lines of list_dir=`ls -t /path/to/dir/` for i in $list_dir; do or ls -t | while read i; do Now, I know that you shouldn't ...
7
votes
8answers
4k views

Bash, remove oldest files

I`m trying to delete old files from directory and leave only 3 newest files. cd /home/user1/test while [ `ls -lAR | grep ^- | wc -l` < 3 ] ; do rm `ls -t1 /home/user/test | tail -1` ...
6
votes
1answer
555 views

Check last time .sh file used

When you run ./myscript.sh is that considered as "access" time? I need to know the last time a script was run, but I'm not sure if this counts as mtime, ctime or atime (differences described here).
6
votes
2answers
1k views

What can you do to a file without triggering the “Change” Timestamp?

What can you do to a file without triggering the "Change" stat? For instance, it appears that simply changing a bit will trigger Change.
6
votes
4answers
191 views

Find newest file. Multiple Filetype restrictions

I want to write a command that gives me the newest file in a directory recursively. But that's not my only limitation. The files has to be an mp3 or a jpg file. (case insensitive prefered) I only need ...
6
votes
3answers
5k views

Determine if a file has been modified

In Linux (currently using ext4 filesystem), how can one check quickly if the contents of a file has been modified without reading any of its contents? Is the stat command a recommended approach? I ...
6
votes
3answers
3k views

How do I set a file's mtime in epoch format?

I know how to get a file's mtime in epoch format: stat --format=%Y <file> But I have not been able to figure out how to set a file's mtime in epoch format. The touch(1) man page appears to ...
6
votes
1answer
1k views

Can you change timestamp format for history command on tcsh

When I run history command (on tcsh), it only prints the TIME portion of the timestamp and omits the date: 3 15:07 echo $PATH 4 15:07 ls -la In bash, you can use HISTTIMEFORMAT ...
6
votes
1answer
3k views

How do I get the difference between two timestamps?

I am creating a simple backup script. I would like to have a message saying "You last backed up x days ago" on login. I can create a file when I do the backup "backup/.last_backup_timestamp" but what ...
5
votes
5answers
5k views

How to get system time with microsecond Resolution

I want to know current system time with microsecond Resolution. date +%s returns Time in seconds since epoch(1-1-1970). How can I get time in microseconds Resolution. How much delay is in querying ...
5
votes
4answers
4k views

Move files by date into different directory using CLI

I have a large number of pictures from an old hard drive that I'm trying to organize. If I run ls -l, I notice all of these files have a creation date of 2012 or before. Ideally, I'd like to move ...
5
votes
3answers
991 views

How to view last 5 lines from last created/modified file?

Every day I have to take backup and update the status to support teams at particular time for which I need to check last 5 lines of last created/modified *.aff file in a directory and update them. ...
5
votes
1answer
3k views

How to understand the unix time format?

How does the Unix time format work? For example, the Unix time for 3:00 PM is: Normal time format <----3:00PM = 1402565420----> Unix Time How can I make it understand the time as 3:00 PM ?
5
votes
2answers
14k views

list all files newer than given timestamp and sort them

I want to list all files (sorted by date) that are newer than timestamp in format 20130207003851 in directory /tmp only. Subdirectories can be omitted. Using SUSE Linux Enterprise Server 11. The ...
5
votes
3answers
435 views

Unix epoch in milliseconds

I'm prepending the Unix epoch with "nanosecond" precision into output of my command as below: $ command | while read line; do d=`date +%s%N`; echo $d $line; done > file I looked around to find ...
5
votes
3answers
2k views

Append human readable timestamp of last edit to filename

I would like to add the time of the last change to the file to its filename using the bash. For example this output of ls -la: -rw-rw-r-- 1 beginner beginner 5382 Dec 1 17:18 B_F1-1.xml should ...
5
votes
3answers
5k views

Delete files based on year

I need to delete all files in a directory that were created in 2009. What command can I use to do that?
5
votes
1answer
119 views

Using File Date/Time as Metadata: Reliable?

Background: I have groups of files in their own directory which I merge into one file in order of their filename. I call them t1.txt, t2.txt, t3.txt... I merge them in order of the integer. Situation:...
5
votes
1answer
473 views

Why are mtime and ctime changing for a directory when a file is modified?

I am learning about atime, ctime, mtime with regard to files and directories. It seems to me that if I modify a file within a directory, I haven't changed the "directory file" itself in its inode or ...
5
votes
2answers
834 views

How to search file based on DAY of week

Actually I need to search for files and folder that were created in 2012 on Friday of every month. I did some attempts using the find command but it didn't work.
5
votes
1answer
2k views

Get “date” to understand a timestamp phrase of a different language

My web-scraping scripts have long enjoyed using date -d to read in human-formatted time and date stamps like "March 11, 1999" and convert to any other format I need via the -s parameter. How might I ...
5
votes
1answer
3k views

On what occasion will inode change?

I checked manual of find , and there's an option -ctime which specify the last modification time of inode. But on what occasion would inode change ? When is that option useful ?