Add number to variable size in Bash

Question

I am trying to find the size of a folder, and add 1M to it. The 1M is just spacing that I need for other reasons.

Here is what I have tried:

echo $($(du -sh myFolder) + 1) # command not found: 170M
echo $(`du -sh myFolder` + 1)  # same as above

I want to be able to save this to a variable so I can use it in a dd call.

Joao Morais · Accepted Answer · 2016-02-12 12:42:11Z

1

echo $(($(du -sb myFolder | cut -f1)+1048576))

du -sb gives a single sumarized result in bytes.

answered Feb 12, 2016 at 11:51

Joao Morais

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2 Comments

This gives me the error, "bad math expression: operator expected at '1157680\n40...'"

@chris13524 edited the answer, a -s (sumarize) was missing.

Hudson Santos · Accepted Answer · 2016-02-12 11:58:10Z

1

Alternatives if you can't use -b as Joao Morais suggested:

expr `du -hs myFolder | awk '{print $1}' | tr -d M` + 1

echo $((`du -hs myFolder | awk '{print $1}' | tr -d M` + 1))

answered Feb 12, 2016 at 11:58

Hudson Santos

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This is only going to work if the -h (human readable) flag finds a size it wants to represent in MBs. I have, for example: du -hs /u6 155G /u6

John Hascall · Accepted Answer · 2016-02-12 17:18:45Z

0

Yet another way:

BLOCKSIZE=1048576 du -s myFolder | awk '{print $1+1}'

or to put in a variable:

mbs=$(BLOCKSIZE=1048576 du -s myFolder | awk '{print $1+1}')

Works on Linux, BSD, and OS X (possibly others).

answered Feb 12, 2016 at 17:18

John Hascall

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