assign only numeric value to variable in unix

Question

In bash script I am taking command line input in alphanumeric values. example: D7, 12D I want to assign these value to some variable but I want only numeric values to be assigned. In above example value should be assigned as 7 and 12

In linux it can be done by

echo "D7" |grep -o '[0-9]*'

I want this should work for both linux,unix servers. Above command doesnt work on solaris box.

Thanks for help

~Ankit

You want GNU grep. The only reason Oracle doesn't change it (AFAIK), is because it would break existing Solaris behavior. Next, try it on AIX, HP-UX, the BSD(s) and Minix. Good luck! — Elliott Frisch
– Elliott Frisch, Commented Oct 2, 2017 at 16:51
Are the letters always confined to a suffix or prefix, or could you get a value like 14D7, in which case should that be treated as 14, 7, or 147? — chepner
– chepner, Commented Oct 2, 2017 at 16:55

JNevill · Accepted Answer · 2017-10-02 16:55:47Z

2

While this doesn't directly answer your question about grep in different environments, you can use sed for this:

echo "D7"  | sed 's/[^0-9]//g'

s/[^0-9]//g says "Replace any thing that isn't a number with nothing"

edited Oct 2, 2017 at 16:55

answered Oct 2, 2017 at 16:51

JNevill

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2 Comments

Elliott Frisch Over a year ago

Well, sure; you could also do that. But OP was asking about grep behavior not being consistent. :)

JNevill Over a year ago

@ElliottFrisch Oh! I didn't read that far. I always got in trouble in school for not reading all of the instructions before jumping into the solution. I feel like I should leave this up here since sed may provide an alternate to the oddball implementations of grep in solaris and all that.

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