How to get the line number of a match?

Question

My aim is to get the line number ($lineof) of a string which matches a line in /etc/crontab.

To give 0 8 * * * Me echo "start working please" and get this is the line number 13 from /etc/crontab.

Given this file /tmp/crontab :

# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# m h dom mon dow user  command
#
0 17 * * * Me echo "end of work"
0 8 * * * Me echo "start working please"
1 3 2 4 2 Me ls -la

I do something like that for the moment:

cat /etc/crontab | grep -v "#" | grep "Me" > /tmp/task.cron
i=1
while read -r content
do
        line=$content
        # lineof=$LINENO
        nbline=${i}
        minute=$(echo "$line" | awk '{print $1}')  #0-59
        hour=$(echo "$line" | awk '{print $2}')    #0-23
        dom=$(echo "$line" | awk '{print $3}')     #1-31
        month=$(echo "$line" | awk '{print $4}')   #1-12
        dow=$(echo "$line" | awk '{print $5}')     #0-6 (0=Sunday)
        cmd=$(echo "$line" | awk '{$1=$2=$3=$4=$5=$6=""; print $0}')    #command
        cmd=$(echo "$cmd" | tr ' ' _)
        str=$str' '$nbline' "'$minute'" "'$hour'" "'$dom'" "'$month'" "'$dow'" "'$user'" "'$cmd'" '
        i=$(($i+1))
done < /tmp/task.cron

$nbline give me the line of the content in /tmp/task.cron

$LINENO give me the line of the current script (which execute the program)

I want $lineof give me the number of the line in /etc/crontab

Answer 1

grep --fixed-strings --line-number "${match}" | cut --delimiter=":" --fields=1

Answer 2

I finally did like this, found alone :

nbline=1
        while read -r content
        do
                line=$content
                if [ "${line:0:1}" != "#" ]; then #if this is not a comment
                        line=$(echo -e "$line" | grep "$user") #$line keep only lines with the $user choose
                        if [ ! -z "$line" ];then #if this is not a void $line
                                minute=$(echo -e "$line" | awk '{print $1}') #0-59
                                hour=$(echo -e "$line" | awk '{print $2}')   #0-23
                                dom=$(echo -e "$line" | awk '{print $3}')    #1-31
                                month=$(echo -e "$line" | awk '{print $4}')  #1-12
                                dow=$(echo -e "$line" | awk '{print $5}')    #0-6 (0=Sunday)
                                cmd=$(echo -e "$line" | awk '{$1=$2=$3=$4=$5=$6=""; print $0}')    #command
                                cmd=$(echo -e "$cmd" | tr ' ' _) #replace space by '_' because it's annoying later
                                str=$str' "'$nbline'" "'$minute'" "'$hour'" "'$dom'" "'$month'" "'$dow'" "'$user'" "'$cmd'" '
                        fi
                fi
                nbline=$(($nbline+1))
        done < /etc/crontab

I don't need to create an other file and get in $nbline the number of current line in loop. And count all line, even if they are void or commented. That's what I wanted.

'#' is the line number of the right content in /etc/crontab.

Answer 3

To print the line number of your match, use the -n option of grep. Since the pattern contains some special characters, use -F to make them be interpreted as fixed strings and not a regular expression:

grep -Fn 'your_line' /etc/crontab

However, since you want to print some message together with the line number, you may want to use awk instead:

awk -v line='your_line' '$0 == line {print "this is the line number", NR, "from", FILENAME}' /etc/crontab

Test

$ cat a
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# m h dom mon dow user  command
#
0 17 * * * Me echo "end of work"
0 8 * * * Me echo "start working please"
1 3 2 4 2 Me ls -la

With awk:

$ awk -v line='0 8 * * * Me echo "start working please"' '$0 == line {print "this is the line number", NR, "from", FILENAME}' a
this is the line number 13 from a

With grep:

$ grep -Fn '0 8 * * * Me echo "start working please"' a13:0 8 * * * Me echo "start working please"
13:0 8 * * * Me echo "start working please"