expr command used to work and stopped

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http://unix.stackexchange.com – I am on SunOS machine trying to get the date string of the past minute, yesterday I used this command I found on the internet expr `date +%Y%m%d%k%M` - 1 which is worked just fine and I saw the output and this is the output I got from my session that is still opened: bash-3.00$ expr `date +%Y%m%d%k%M` - 1 201303131641 Now I am trying to run this command on the same session and I got this output: bash-3.00$ expr `date +%Y%m%d%k%M` - 1 expr: syntax error My machine is running this OS: bash-3.00$ uname -a SunOS mySunOS 5.10 Generic_144488-11 sun4v sparc SUNW,Netra-T2000 I think there (HowTos)