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touch for you BSD gurus

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  touch for you BSD gurus Robert Peirce <bob@peirce-family.com> - 2011-06-12 12:54 -0400
    Re: touch for you BSD gurus Bob Harris <nospam.News.Bob@remove.Smith-Harris.us> - 2011-06-12 20:26 -0400
      Re: touch for you BSD gurus Robert Peirce <bob@peirce-family.com> - 2011-06-13 07:57 -0400
        Re: touch for you BSD gurus Bob Harris <nospam.News.Bob@remove.Smith-Harris.us> - 2011-06-13 21:57 -0400
          Re: touch for you BSD gurus Robert Peirce <bob@peirce-family.com> - 2011-06-14 22:00 -0400

#374 — touch for you BSD gurus

I have two backup systems for my photos.  I try to keep them 
synchronized.  I use tar to create a compressed file of any photos taken 
since a TS (time stamp) file.  Then I touch TS to bring it to today.

The problem is, depending on how good I am about adding photos to my 
library, some photos may already be older than the time stamp.  One 
solution is to manually touch TS to make sure it is old enough.  A 
better way would be if I could touch TS with a date, say, one month 
earlier.

Obviously, I could create the appropriate date string and use "touch -t 
date TS," but I would really prefer to be able to just specify a 
negative increment.  The man page doesn't indicate this as an option.  
Is there any way to do it?

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#377

In article <bob-F0B857.12544012062011@5ad64b5e.bb.sky.com>,
 Robert Peirce <bob@peirce-family.com> wrote:

> I have two backup systems for my photos.  I try to keep them 
> synchronized.  I use tar to create a compressed file of any photos taken 
> since a TS (time stamp) file.  Then I touch TS to bring it to today.
> 
> The problem is, depending on how good I am about adding photos to my 
> library, some photos may already be older than the time stamp.  One 
> solution is to manually touch TS to make sure it is old enough.  A 
> better way would be if I could touch TS with a date, say, one month 
> earlier.
> 
> Obviously, I could create the appropriate date string and use "touch -t 
> date TS," but I would really prefer to be able to just specify a 
> negative increment.  The man page doesn't indicate this as an option.  
> Is there any way to do it?

You can do this with a little script

#!/usr/bin/env bash
typeset delta="$1"
shift
touch -t $(date -v ${delta} +%Y%m%d%H%M.%S) "$@"

Now give the file a name (mytouch) and make it executable
(chmod +x mytouch).

Using the "man date" -v option, you can specify a negative time 
offset to the current time.

So if you want to back date the file by 1 month you would

    mytouch -1m image1.jpg image2.jpg image3.jpg ....

What to move the time back a year

    mytouch -1y image1.jpg image2.jpg image3.jpg ....

Just a couple of days

    mytouch -7d image1.jpg image2.jpg image3.jpg ....

Want to move forward in time, change the minus to a plus :-)

The valid suffix values are "y, m, w, d, H, M or S", for year, 
month, week, day, Hour, Minute, Second.

Have fun.

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#379

In article 
<nospam.News.Bob-F405BF.20261212062011@news.eternal-september.org>,
 Bob Harris <nospam.News.Bob@remove.Smith-Harris.us> wrote:

> You can do this with a little script
> 
> #!/usr/bin/env bash
> typeset delta="$1"
> shift
> touch -t $(date -v ${delta} +%Y%m%d%H%M.%S) "$@"
> 
> Now give the file a name (mytouch) and make it executable
> (chmod +x mytouch).

I'm doing something like that.

I=`date -v+9m -v-1y "+%y%m%d"`
touch -t ${I}2359 TS

I was hoping there might be an arg I could give directly to touch.

I had to add 9 mos and subtract 1 year to have it handle year end 
properly.  For example, trying to go 3 months back from 2/11 resulted in 
11/11 instead of 11/10.

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#384

In article <bob-A36DFD.07572913062011@5ad64b5e.bb.sky.com>,
 Robert Peirce <bob@peirce-family.com> wrote:

> In article 
> <nospam.News.Bob-F405BF.20261212062011@news.eternal-september.org>,
>  Bob Harris <nospam.News.Bob@remove.Smith-Harris.us> wrote:
> 
> > You can do this with a little script
> > 
> > #!/usr/bin/env bash
> > typeset delta="$1"
> > shift
> > touch -t $(date -v ${delta} +%Y%m%d%H%M.%S) "$@"
> > 
> > Now give the file a name (mytouch) and make it executable
> > (chmod +x mytouch).
> 
> I'm doing something like that.
> 
> I=`date -v+9m -v-1y "+%y%m%d"`
> touch -t ${I}2359 TS
> 
> I was hoping there might be an arg I could give directly to touch.

not that I know of.  But then again a simple script as I showed 
above gives you your own mytouch command.  That is the beauty of 
Unix.  The ability to combine simple commands into more complex 
forms that suit your needs.

> I had to add 9 mos and subtract 1 year to have it handle year end 
> properly.  For example, trying to go 3 months back from 2/11 resulted in 
> 11/11 instead of 11/10.

I do not have any problems using any number of months to go back 
years.  For example:

    date -v -165d
    Thu Dec 30 21:51:55 EST 2010

    date -v -530d
    Wed Dec 30 21:52:59 EST 2009

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#385

In article 
<nospam.News.Bob-8E77F7.21570213062011@news.eternal-september.org>,
 Bob Harris <nospam.News.Bob@remove.Smith-Harris.us> wrote:

> I do not have any problems using any number of months to go back 
> years.  For example:
> 
>     date -v -165d
>     Thu Dec 30 21:51:55 EST 2010
> 
>     date -v -530d
>     Wed Dec 30 21:52:59 EST 2009

You're right!  I don't know why it didn't work right for me the first 
time.  I just tried date -v -7m and got

Sun Nov 14 21:57:46 EST 2010

I wonder if the formatting had anything to do with it.

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