Escaping Special characters

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# 1  
Old 10-26-2009
Escaping Special characters

I want to append the following line to /var/spool/cron/root:
*/7 * * * * /root/'Linux CPU (EDF).sh' > /dev/null 2>&1

How to accomplish this using echo?

---------- Post updated at 04:09 PM ---------- Previous update was at 04:07 PM ----------

"Linux CPU (EDF)" is actually stored in a variable named Service_Name

---------- Post updated at 04:13 PM ---------- Previous update was at 04:09 PM ----------

I am using the command:

echo "*/7 * * * * /root/\'"$Service_Name".sh\' >/dev/null 2>&1" >> /var/spool/cron/root

# 2  
Old 10-26-2009

echo "*/7 * * * * /root/'$Service_Name'.sh > /dev/null 2>&1" >> root

It's generally not a good idea to manually modify the crontab file in this way. You should use crontab.

Last edited by Scott; 10-26-2009 at 06:49 PM..
# 3  
Old 10-26-2009
But the Service_Name variable contains "Linux CPU (EDF)", which has got spaces in between. I need to escape those spaces..
# 4  
Old 10-26-2009
echo "*/7 * * * * /root/'$Service_Name'.sh > /dev/null 2>&1" >> root

You don't need to escape anything.

A=" '1 2 3' "

echo $A
'1 2 3'

# 5  
Old 10-26-2009
I thought single quote reduces the significance of special characters including $.
# 6  
Old 10-26-2009
Not when they're enclosed in double quotes. The opposite isn't true.

A=" '1 2 3' "

echo "$A"
'1 2 3'

A=' "1 2 3" '
echo $A
"1 2 3"

echo '$A'

# 7  
Old 10-26-2009
ksspl-RandD:~$ echo $x

ksspl-RandD:~$ echo '$x'

---------- Post updated at 04:59 PM ---------- Previous update was at 04:55 PM ----------


If we include something inside of double-quotes, everything loses its special meaning except for the variable operator ($), the back-slash (\), the back-tick (`), and the double-quote itself.
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