Unexpected bash function output

Question

I have written a 'to_upper' function using bash scripting:

to_upper() {

    local string=$1
    echo $string | tr "[:lower:]" "[:upper:]"
    return 0
}

However, the output of:

VAL=bla
echo $(to_upper bla)
echo $(to_upper $VAL)

is

BLA
1

Does anyone know what is going on here?

NOTE: It seems my example does not reproduce my error. However, what I do have is this situation:

DEVICE_STATUS=$(get_device_status)
echo $DEVICE_STATUS $(to_upper $DEVICE_STATUS)

The output is then:

active 1

My example seems to not reproduce the problem, but it's there on my script.

NOTE 2: I fixed the problem; it was some grep output on the get_device_status function which ended up on $DEVICE_STATUS.

neither in my bash, GNU bash, version 4.2.37(2)-release (x86_64-unknown-linux-gnu) — user237419
– user237419, Commented Nov 14, 2012 at 9:44
You don't need to call the function in sub-process. Instead of "echo $(to_upper bla)" you can go "to_upper bla". — dimir
– dimir, Commented Nov 14, 2012 at 9:44
Please tell us what shell and version are you using (and perhaps also platform). — dimir
– dimir, Commented Nov 14, 2012 at 9:45
To all: please see my edit (I'm on ubuntu 12.04, bash 4.2.24) — user1641774
– user1641774, Commented Nov 14, 2012 at 9:46

user1641774 · Accepted Answer · 2012-11-14 10:21:28Z

1

I solved my own problem: in the get_device_status function there was a grep command which was outputting junk to $DEVICE_STATUS. Redirecting the grep output to /dev/null solved the problem.

I am not quite sure in this case why $DEVICE_STATUS picked up the correct value on the echo but not on the call to to_upper.

answered Nov 14, 2012 at 10:21

user1641774

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