Simple bash scripting help needed..

Question

I want to learn som simple bash scripting in order to automate various tasks.. Im totally noob, so bear with me
First of all I would like to set configs without using nano.. is there a simple command for this? For example if i want change my hostname in /etc/rc.conf.. how can i print the current vallue and how can i change it`?
i was thinking something like this to get the current value:
# cat /etc/rc.conf | grep HOSTNAME=
which returns HOSTNAME="myhostname"
how can i change this value with one or more commands whitout touching the rest of the file?

Answer 1

abesto wrote:
A slightly naive solution:
CHOICE="lisa"
NAMES="homer marge lisa bart maggie"
if [ "`echo \" $NAMES \" | grep \" $CHOICE \"`" ]; then
echo "this is how you do it"
fi
The extra spaces inside the escaped quotes are to ensure that only a whole word is "matched".
You can also replace the elif's with a loop through a list of "the other variables". Then you'd use the loop variable instead of $CHOICE above.
grep can check on word-bounderies with \< and \>, or with the -w switch. The -q switch suppresses any messages and exits with exit-code 0 when the first match is found:
if echo "${NAMES}" | grep -qw "${CHOICE}"; then
Nice and readable, should work, but i haven't tested it
EDIT:
Procyon wrote:CHOICE="lisa"
NAMES="homer marge lisa bart maggie"
if [[ $NAMES =~ $CHOICE ]]; then echo match; fi
This one also matches elisa, ie. no check on word bounderies. You should be carefull with that
Last edited by klixon (2009-04-23 09:40:22)