Zero pad numbers in `cal` (or `gcal`) output

bashcommand lineunix

This seemed pretty easy, but I have not found a good way to do it.

In Terminal, cal will give this output:

September 2015 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

That is, it will show the calendar for the current month.

I would like to have it display like so:

September 2015 Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

This seems like it would be fairly easy to do, but so far I can’t crack it.

Initially I thought I would just look for the numbers 1-9 with one space on either side. That works… except if the number is on Saturday, or Sunday, because then there's no leading/trailing padding.

So I'm at a loss. I even looked at GNU cal which seems to have a bazillion options, but I couldn't find one for this.

I'm sure there's a way to do this with sed/awk/tr/etc but I can't figure it out. Would prefer as “lightweight” of a solution as possible, as this is something that will run frequently, but I'm not adverse to installing something else via brew if it can do a better/ more efficient job.

Best Answer

sed to the rescue:

pse@Mithos:~$ cal 09 2015 | sed -e 's/ \([[:digit:]]\) /0\1 /g' \
                                -e 's/ \([[:digit:]]\)$/0\1/g'
   September 2015
Su Mo Tu We Th Fr Sa
      01 02 03 04 05
06 07 08 09 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30

Combining the two sed commands into one is left as an exercise to the reader.

Related Solutions

Bash shell script to locate and remove substring within a filename

ls | perl -nl -e '/(.*)(S[0-9]+E[0-9]+).*(\.mp4)/ && print "mv \"" . $_ . "\" \"". $1 . $2 . $3 . "\""'

How does this work? First ls outputs the list of files, one per line, like so:

The.Big.Bang.Theory.S01E01.xxxxxxxx.mp4
The.Big.Bang.Theory.S01E02.somecrap.mp4
The.Big.Bang.Theory.S04E12.otherjunk.mp4

Then perl -nl splits this into lines, feeding each to the regex, much like awk*. The regex captures 3 groups (denoted by parentheses), first the bit before SxxEyy, then that, then the file suffix. It then simply assembles a mv command suitable for renaming the files, like so:

mv "The.Big.Bang.Theory.S01E01.xxxxxxxx.mp4" "The.Big.Bang.Theory.S01E01.mp4"
mv "The.Big.Bang.Theory.S01E02.somecrap.mp4" "The.Big.Bang.Theory.S01E02.mp4"
mv "The.Big.Bang.Theory.S04E12.otherjunk.mp4" "The.Big.Bang.Theory.S04E12.mp4"

This can then be inspected and once you're satisfied it does what you want, piped into a shell by appending: | sh.

*awk would normally be a good tool to use for this, but sadly only GNU awk supports regex capture groups and Mac OS X doesn't include gawk by default.

Foolproof way of extracting .pkg files

It's easy enough to create a shell script which checks for a few conditions and then takes the appropriate action.

I've put mine at http://dl.dropbox.com/u/18414/bin/unpkg.sh but will copy the initial version below:

#!/bin/zsh
#
#   Author:     Timothy J. Luoma
#   Email:      luomat at gmail dot com
#   Date:       2011-12-29
#
#   Purpose:    extract .pkg files, either xar archives or directory
#               
#   URL:       http://dl.dropbox.com/u/18414/bin/unpkg.sh
#   
#   See also:  http://apple.stackexchange.com/questions/34957/foolproof-way-of-extracting-pkg-files

NAME="$0:t"

    # Brief explanation of how program works
USAGE="$NAME is meant to extract package files. (Filenames must end in .pkg). Can handle both .pkg directories or xar archives.

Usage: $NAME /path/to/foo.pkg
"

    # in case of emergency, report error and exit
die ()
{
    echo "$NAME: $@"
    exit 1
}

    # if not given any input, explain how to use it
if [ "$#" = "0" ]
then
        die "$USAGE"    
fi

    # put whatever we get as an argument into a variable
INPUT="$@"

    # does the input actual refer to an existing file?
    # if not, exit
[[ -e "$INPUT" ]]       || die "$INPUT does not exist"

    # get the extension of the input. i.e. if we are
    # given "foo.pkg" this will just be "pkg"
EXT="$INPUT:e"

    # check to make sure that the extension is 'pkg'
    # because that's what we're looking for
[[ "$EXT" = "pkg" ]]    || die "$INPUT is not a pkg"

TYPE=`file -b "$INPUT"`

case "$TYPE" in 
    directory)
                gzcat "$INPUT/Contents/Archive.pax.gz" | pax -r

    ;;

    "xar archive - version 1")
                # Put whatever commands you want here
                :
    ;;


    *)
            die "$USAGE"    
    ;;

esac



exit 0
#EOF

zsh has been included in Mac OS X for several releases now. I prefer it over /bin/sh because… well, let's not get into a "my shell is better than your shell" war, because my shell would win :-)

In any event, zsh makes things a little easier and a little nicer, and it's included, so there's no reason not to use it, IMO. Especially for a OS X-specific script like this.

This was tested on 10.7.

Best Answer

Related Solutions

Bash shell script to locate and remove substring within a filename

Foolproof way of extracting .pkg files

Related Question