Convert input string to date in shell script

Question

My shell script:

#!/bin/bash
echo "$1";
startd=$(date -d "$1" +"%Y%m%d"); 
echo "$startd";

My command:

sudo ./test.sh "20151010"

The output:

20151010 
20150213

it printed todays date instead of printing the input date any idea?

Solution 1

The OS X version of date uses the -f option to parse a formatted date/time:

date -j -f '%Y%m%d' "$1" +'%Y%m%d'

The -j option causes it to just print the time, not try to set the system clock. So the full script would be:

#!/bin/bash
echo "$1";
startd=$(date -j -f '%Y%m%d' "$1" +'%Y%m%d'); 
echo "$startd";

Here's a transcript:

$ ./testdate.sh 20151010
20151010
20151010

Solution 2

If you are trying to format date on OS X, you can try this:

date -j -f "%Y%m%d" "20151010"

I get the following output:

Sat Oct 10 17:27:28 CDT 2015

Comments

[vinc17]

I have no such problem with date under Linux. You may need to install the GNU Coreutils and use date from them. BTW, you do not need sudo.

[Barmar]

The OS X version of date doesn't parse arbitrary date formats like the GNU version does.

[PUG]

it turns out developing these scripts on osx won't do for me than because production env is linux, And i want the linux version of scripts