Commands tagged modification time (4)

  • Sometimes when copying files from one place to another, the timestamps get lost. Maybe you forgot to add a flag to preserve timestamps in your copy command. You're sure the files are exactly the same in both locations, but the timestamps of the files in the new home are wrong and you need them to match the source. Using this command, you will get a shell script (/tmp/retime.sh) than you can move to the new location and just execute - it will change the timestamps on all the files and directories to their previous values. Make sure you're in the right directory when you launch it, otherwise all the touch commands will create new zero-length files with those names. Since find's output includes "." it will also change the timestamp of the current directory. Ideally rsync would be the way to handle this - since it only sends changes by default, there would be relatively little network traffic resulting. But rsync has to read the entire file contents on both sides to be sure no bytes have changed, potentially causing a huge amount of local disk I/O on each side. This could be a problem if your files are large. My approach avoids all the comparison I/O. I've seen comments that rsync with the "--size-only" and "--times" options should do this also, but it didn't seem to do what I wanted in my test. With my approach you can review/edit the output commands before running them, so you can tell exactly what will happen. The "tee" command both displays the output on the screen for your review, AND saves it to the file /tmp/retime.sh. Credit: got this idea from Stone's answer at http://serverfault.com/questions/344731/rsync-copying-over-timestamps-only?rq=1, and combined it into one line. Show Sample Output


    5
    find . -printf "touch -m -d \"%t\" '%p'\n" | tee /tmp/retime.sh
    dmmst19 · 2012-11-05 20:32:05 2
  • Here's a way to wait for a file (a download, a logfile, etc) to stop changing, then do something. As written it will just return to the prompt, but you could add a "; echo DONE" or whatever at the end. This just compares the full output of "ls" every 10 seconds, and keeps going as long as that output has changed since the last interval. If the file is being appended to, the size will change, and if it's being modified without growing, the timestamp from the "--full-time" option will have changed. The output of just "ls -l" isn't sufficient since by default it doesn't show seconds, just minutes. Waiting for a file to stop changing is not a very elegant or reliable way to measure that some process is finished - if you know the process ID there are much better ways. This method will also give a false positive if the changes to the target file are delayed longer than the sleep interval for any reason (network timeouts, etc). But sometimes the process that is writing the file doesn't exit, rather it continues on doing something else, so this approach can be useful if you understand its limitations.


    1
    while [ "$(ls -l --full-time TargetFile)" != "$a" ] ; do a=$(ls -l --full-time TargetFile); sleep 10; done
    dmmst19 · 2015-05-09 03:19:49 1
  • Create a bash script to change the modification time for each file in 'files.txt' such that they are in the same order as in 'files.txt' File name for bash script specified by variable, 'scriptName'. It is made an executable once writing into it has been completed. Show Sample Output


    1
    scriptName="reorder_files.sh"; echo -e '#!/bin/sh\n' > "${scriptName}"; cat files.txt | while read file; do echo "touch ${file}; sleep 0.5;" >> "${scriptName}"; done; chmod +x "${scriptName}";
    programmer · 2016-04-19 11:52:00 3

  • 0
    find /home/fizz -type f -printf '%TY-%Tm-%Td %TT %p\n' | sort
    fizz · 2009-05-20 10:45:39 2

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands


Check These Out

search for a file in PATH
Also searches for aliases and shell builtins

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested

Extract all 404 errors from your apache accesslog (prefix lines by occurrences number)

Print a random 8 digit number

continuously check size of files or directories
very handy if you copy or download a/some file(s) and want to know how big it is at the moment

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested

Set OS X X11 to use installed Mathematica fonts

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

ping MAC ADDRESS
# first install arp-scan if not have it arp-scan 10.1.1.0/24 .... show ip+mac in localnet awk '/00:1b:11:dc:a9:65/ {print $1}' .... get ip associated with MAC ` backtick make do command substitution passing ip to command ping

Easily decode unix-time (funtion)
More recent versions of the date command finally have the ability to decode the unix epoch time into a human readable date. This function makes it simple to utilize this feature quickly.


Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: