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Thread: Eliminate leading zero in Bash

  1. #1
    Join Date
    Feb 2007
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    Eliminate leading zero in Bash

    Hi,

    I am using bash and need to eliminate the leading zero in the current month: $( date +'%m')
    For example, now is September, and I need it to give me '9', not '09', so I can use the month in calculations.

    Can anyone please help?

    Thanks!!!

  2. #2
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    Re: Eliminate leading zero in Bash

    Code:
    ~$ date +'%-m'
    9
    Code:
    ~$ date --help
    Usage: date [OPTION]... [+FORMAT]
      or:  date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]
    Display the current time in the given FORMAT, or set the system date.
    
      -d, --date=STRING         display time described by STRING, not `now'
      -f, --file=DATEFILE       like --date once for each line of DATEFILE
      -r, --reference=FILE      display the last modification time of FILE
      -R, --rfc-2822            output date and time in RFC 2822 format.
                                Example: Mon, 07 Aug 2006 12:34:56 -0600
          --rfc-3339=TIMESPEC   output date and time in RFC 3339 format.
                                TIMESPEC=`date', `seconds', or `ns' for
                                date and time to the indicated precision.
                                Date and time components are separated by
                                a single space: 2006-08-07 12:34:56-06:00
      -s, --set=STRING          set time described by STRING
      -u, --utc, --universal    print or set Coordinated Universal Time
          --help     display this help and exit
          --version  output version information and exit
    
    FORMAT controls the output.  Interpreted sequences are:
    
      %%   a literal %
      %a   locale's abbreviated weekday name (e.g., Sun)
      %A   locale's full weekday name (e.g., Sunday)
      %b   locale's abbreviated month name (e.g., Jan)
      %B   locale's full month name (e.g., January)
      %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
      %C   century; like %Y, except omit last two digits (e.g., 20)
      %d   day of month (e.g., 01)
      %D   date; same as %m/%d/%y
      %e   day of month, space padded; same as %_d
      %F   full date; same as %Y-%m-%d
      %g   last two digits of year of ISO week number (see %G)
      %G   year of ISO week number (see %V); normally useful only with %V
      %h   same as %b
      %H   hour (00..23)
      %I   hour (01..12)
      %j   day of year (001..366)
      %k   hour, space padded ( 0..23); same as %_H
      %l   hour, space padded ( 1..12); same as %_I
      %m   month (01..12)
      %M   minute (00..59)
      %n   a newline
      %N   nanoseconds (000000000..999999999)
      %p   locale's equivalent of either AM or PM; blank if not known
      %P   like %p, but lower case
      %r   locale's 12-hour clock time (e.g., 11:11:04 PM)
      %R   24-hour hour and minute; same as %H:%M
      %s   seconds since 1970-01-01 00:00:00 UTC
      %S   second (00..60)
      %t   a tab
      %T   time; same as %H:%M:%S
      %u   day of week (1..7); 1 is Monday
      %U   week number of year, with Sunday as first day of week (00..53)
      %V   ISO week number, with Monday as first day of week (01..53)
      %w   day of week (0..6); 0 is Sunday
      %W   week number of year, with Monday as first day of week (00..53)
      %x   locale's date representation (e.g., 12/31/99)
      %X   locale's time representation (e.g., 23:13:48)
      %y   last two digits of year (00..99)
      %Y   year
      %z   +hhmm numeric time zone (e.g., -0400)
      %:z  +hh:mm numeric time zone (e.g., -04:00)
      %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)
      %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
      %Z   alphabetic time zone abbreviation (e.g., EDT)
    
    By default, date pads numeric fields with zeroes.
    The following optional flags may follow `%':
    
      -  (hyphen) do not pad the field
      _  (underscore) pad with spaces
      0  (zero) pad with zeros
      ^  use upper case if possible
      #  use opposite case if possible
    
    After any flags comes an optional field width, as a decimal number;
    then an optional modifier, which is either
    E to use the locale's alternate representations if available, or
    O to use the locale's alternate numeric symbols if available.
    
    Examples:
    Convert seconds since the epoch (1970-01-01 UTC) to a date
      $ date --date='@2147483647'
    
    Show the time on the west coast of the US (use tzselect(1) to find TZ)
      $ TZ='America/Los_Angeles' date
    
    Show the local time for 9AM next Friday on the west coast of the US
      $ date --date='TZ="America/Los_Angeles" 09:00 next Fri'
    
    Report date bugs to bug-coreutils@gnu.org
    GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
    General help using GNU software: <http://www.gnu.org/gethelp/>
    For complete documentation, run: info coreutils 'date invocation'
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  3. #3
    Join Date
    Jul 2007
    Location
    Poland
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    Ubuntu 14.04 Trusty Tahr

    Re: Eliminate leading zero in Bash

    post above solves the problem but here is some trivia which may be useful in other scenarios
    leading zeros make bash assume the number is in base 8 system.
    In that case you can force it to use base 10
    Code:
    $ x=09; echo $(( 10#$x+12 ))
    21
    btw, what kind of calculations do you need? because it's possible you are reinventing the wheel.
    Last edited by Vaphell; September 2nd, 2012 at 10:10 PM.
    if your question is answered, mark the thread as [SOLVED]. Thx.
    To post code or command output, use [code] tags.
    Check your bash script here // BashFAQ // BashPitfalls

  4. #4
    Join Date
    Feb 2007
    Beans
    5

    Re: Eliminate leading zero in Bash

    It works! Thank you guys for your help.

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