Help on simple shell script


 
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# 1  
Old 05-07-2017
Help on simple shell script

Hello,

I need to create one very simple shell script that checks if the first character of the file ./pump.txt is 0 and in that case gives a message.
If the first character is instead 1, it does give a different message.

I have written:
Code:
irr= head -c 1  ./pump.txt
if [[ "$irr" == "0" ]]; then
        echo "!!!!!!!!!! Disabled"
else
        echo "Enabled"
fi

It does not work.


Ps, the file ./pump.txt is generated by the following commands:
Code:
echo "1" > "./pump.txt"
echo "0" > "./pump.txt"

Can you please help me?
Thanks,
daniele

Last edited by DukeNuke2; 05-07-2017 at 04:42 PM..
# 2  
Old 05-07-2017
Quote:
Originally Posted by dcaccount
Hello,

I need to create one very simple shell script that checks if the first character of the file ./pump.txt is 0 and in that case gives a message.
If the first character is instead 1, it does give a different message.
I have written:
Code:
irr= head -c 1  ./pump.txt
if [[ "$irr" == "0" ]]; then
        echo "!!!!!!!!!! Disabled"
else
        echo "Enabled"
fi

It does not work.


Ps, the file ./pump.txt is generated by the following commands:
either echo "1" > "./pump.txt" or
echo "0" > "./pump.txt"

Can you please help me?
Thanks,
daniele
Try
Code:
irr=$(head -c 1  ./pump.txt)

Note: No space between `='.
# 3  
Old 05-07-2017
Please wrap your code in "code" tags!
You want a sub command
Code:
irr=$(head -c 1 ./pump.txt)

or in backticks
Code:
irr=`head -c 1 ./pump.txt`

More elegant: read the first line
Code:
read irr < ./pump.txt

# 4  
Old 05-07-2017
Thanks for helping, it works!
# 5  
Old 05-07-2017
Or, read just one char:
Code:
read -n1 irr < ./pump.txt

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