Get count of lines in scripts (shell)

If you have tried to get the count of lines in file, the you would know about “nl” or “wc -l”. But as you are aware these give you number of lines with other details as well and you need to post process the number to make sure that you have only number and nothing else. In such cases, it is useful to use the count feature of grep and here is a shorthand to get the count of lines in any shell script:

lines=$(grep -c . <filename>)

nice little bash function to search for running processes

Here is a nice little handy function that I use very regurlarly.

You can use this function with parameter to just grep for that or just type psa to see all the running processes.

Just put this in your .bashrc file.

You might find it useful:

 

psa () 
{ 
    if [[ $1 == "" ]]; then
        ps -eaf;
    else
        ps -eaf | grep --color=auto -i $1;
    fi
}

Raspberry Pi automate certain tasks – script example

Now, if you have followed these :

fetchmail

ssmtp

Then you already have a working system for sending and receiving mail. Now, you can set the mda in the fetmailrc to a script which can do few things for you. The script below will get a page and mail it to you, if you have the subject as “get” and send “wake on LAN” to desired PC if you have subject as “wol”. Cool 🙂

Original idea from here.

Here is the script:

#!/bin/bash

expectedFrom=""
expectedFrom2=""
homePC="MAC Here"

mailHelp() {
	sendMail $1 "Help - Possible Commands" "Help"
}

sendMail() {
	echo "To: "$1 > $tmpMail
	echo "From: From address here" >> $tmpMail
	echo "Subject: "$2 >> $tmpMail
	echo "Content-Type: text/html" >> $tmpMail
	echo "" >> $tmpMail
	echo $3 >> $tmpMail
	cat $tempMail >> $tmpMail
	cat $tmpMail|/usr/sbin/ssmtp  $1
}
#here we start the actual processing

rightSender=0
sender=""
tmpFile=/tmp/mailtemp
tmpMail="/var/tmp/mailtxt.txt"
tempMail="/tmp/tosend.txt"
>$tempMail
>$tmpFile
>$tmpMail

#Write the mail to tmpFile
while read line
do
	echo $line >> $tmpFile
done

grep "From:" $tmpFile | grep $expectedFrom > /dev/null
if [ $? -eq 0 ]; then
	rightSender=1
	sender=$expectedFrom
fi

grep "From:" $tmpFile | grep $expectedFrom2 > /dev/null
if [ $? -eq 0 ]; then
	rightSender=1
	sender=$expectedFrom2
fi

if [ $rightSender -eq 1 ]; then
	task=`grep "Subject:" $tmpFile`
	task=${task:9}
	task=`echo $task | tr [:upper:] [:lower:]`

	echo $task | grep "help" > /dev/null
	if [ $? -eq 0 ]; then
		mailHelp $sender
		exit
	fi
fi
while read line
do
	if [[ $line =~ ^$|^Content*:*|^charset=*|^--=* ]]; then
		continue;
	fi
	echo "LINE :: $line"
	case $task in
		get)
			cmd="wget -o /dev/null -O - $line"
		;;
		wol)
			cmd="sudo etherwake $$line"
		;;
		*)
			cmd="$line"
		;;
	esac
	eval $cmd >> $tempMail
done < <( sed '1,/^$/ d' $tmpFile|sed '/^--$/,$ d')
sendMail $sender "Output result of command $task" "Happy Hacking"

rm $tmpFile
rm $tmpMail
rm $tempMail
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