Append Current Date To Filename in Bash Shell

Posted on in Categories , last updated April 26, 2011

How do I append current date (mm_dd_yyyy format) to a filename (e.g., backup_mm_dd_yyyy.sql) under UNIX like operating systems?

To get the current date in mm_dd_yyyy format use the following date format syntax:

date +"%m_%d_%Y"

You can store this to a variable name:

now=$(date +"%m_%d_%Y")

OR

now=`date +"%m_%d_%Y"`

Finally, you can create a filename as follows:

now=$(date +"%m_%d_%Y")
echo "Filename : /nas/backup_$now.sql"

Sample outputs:

Filename : /nas/backup_04_27_2010.sql

You can create a shell script as follows:

#!/bin/bash
_now=$(date +"%m_%d_%Y")
_file="/nas/backup_$_now.sql"
echo "Starting backup to $_file..."
# mysqldump -u admin -p'myPasswordHere' myDbNameHere > "$_file"

17 comment

  1. This is not working for me.
    It always says “date: zusätzlicher Operand „%Y-%m-%d“”, which means “date: extra operand „%Y-%m-%d“” or something like that.

    here is my script:
    #! /bin/bash
    current_date=$(date + “%Y-%m-%d)
    file=”/mnt/Daten/piBackup/Arch${current_date}.img”
    echo “Starting backup to $file…”
    dd bs=1M if=/dev/mmcblk0 |pv| dd of=$file

    You know what i’ve done wrong?

    1. There should not be a whitespace between + and the format string on line 3. Change $(date + “%Y-%m-%d”) to $(date +”%Y-%m-%d”).

  2. Great blog post! Thank you very much!

    I wrote the following script to save the screenshots with date and time in the filename similar as in Mac OS X:

    #!/bin/bash
    echo "Taking screenshot via adb from connected Android device..."
    dateAndTime=$(date +"%Y-%m-%d at %H.%M.%S")
    filename="ADB Screen $dateAndTime.png"
    adb shell screencap -p | perl -pe 's/\x0D\x0A/\x0A/g' > "$filename"
    echo "Successfully saved screenshot to $filename"
    exit 0
    
  3. You can also avoid the bash shell altogether and put the one line in your crontab like:

    mysqldump --user=[user] --password=[pass] Database>Database_`date +"%m%d%y"`.sql
  4. Try this on for size, in bash:
    ——
    bkup ()
    {
    ## shell function, placed in your profile
    STAMP=`date +%m%d%y-%H%M%S`
    cp -i ${1}{,.${BKUP_DATE_STAMP}}
    }
    ——

    Place the above function in your .profile or .bash_profile or .bashrc. Wherever you like or paste it into a command line on the terminal. Then use it like this:

    touch name.conf
    bkup name.conf

    To check and see if it worked,

    ls -l name.conf*

    The advantage to this approach is that if you are backing up a file in a subdirectory:

    bkup /path/to/the/file/name.conf
    ls -l /path/to/the/file/name.conf*

    -rw-r–r– 1 unixDude unixDude 0 Sep 13 21:21 /path/to/the/file/name.conf
    -rw-r–r– 1 unixDude unixDude 0 Sep 13 21:23 /path/to/the/file/name.conf.091314-211838

    Now, the challenge is to backup the file and then vi it or what you will, within the same function.

    UD-

  5. I am very newbie about bash.
    Why there’s a plus sign in front of the pattern?
    date +”%m_%d_%Y”

    Thanks

  6. How do you put a string and the date in one line, e.g.
    MyDate=’Mystring’ date +”%Y-%m-%d_%H.%m”
    echo $MyDate
    I know it’s not working, but how do you do that?

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