Get "n" number of lines from the specified file and store the output to the new file

Shell Programming and Scripting
1

Hiii.

How are you all. .. I have started to learn bash scripting.. . and I am pretty much trying to execute this script which I am still not successful.. .

This is what I am trying to do. ..

need to get "n" number of lines from the specified file and store the output to the new file in some other specified directory.. .and if the file with the same name exists. .the script should create a new file with date / count to the new file.

Below is the script I came up with, ,,there may be many mistakes. . . . but . .through mistakes you learn

Can someone help me here. . .THanks !!!!!!!!

#!/bin/bash

export SAVEPATH="/home/zshaikh/"
export FILENAME=$(basename $1)

COUNT=1

if [ -r $FILE ]; then

	tail -n $2 $1 >> ${SAVEPATH}${FILENAME}


elif [ -r ${SAVEPATH}${FILENAME} ]; then

	tail -n $2 $1 > ${PATH}${FILENAME}.$(date +%Y%m%d)


elif [ -r ${SAVEPATH}${FILENAME}.$(date +%Y%m%d) ]; then

	tail -n $2 $1 > ${PATH}${FILENAME}.$(date +%Y%m%d).$COUNT


elif [ -r ${SAVEPATH}${FILENAME}.$(date +%Y%m%d).$COUNT ]; then

	COUNT=`expr $COUNT + 1`

	tail -n $2 $1 > ${PATH}${FILENAME}.$(date +%Y%m%d).$COUNT


fi
2

Did you try executing this script??

For me it seems OK. :slight_smile:

3

Hii . . .

When I try executing the script, I get the following errors :

basename : command not found.

and

/home/zshaikh/ is a directory

i m still not able to figure it out whats wrong:(

4

I think the second error is because there are nothing in $FILENAME because of the first error with basename. This is how to get basename another way: ${1##*/} (if you want it from $1).

I don't understand PATH and FILE in your script, they don't get any values?

I also think you must have a loop in the last part:

should be:

...
else
  while [ -r ${SAVEPATH}${FILENAME}.$(date +%Y%m%d).$COUNT ]; do
    COUNT=`expr $COUNT + 1`
  done
  tail -n $2 $1 > ${PATH}${FILENAME}.$(date +%Y%m%d).$COUNT
fi
5

ok. .. so I re-edited the script. . .

#!/bin/bash

# USE :
#script_name log_path no_of_lines

export PATH="/home/xosh/"
export FILENAME=$(/usr/bin/basename $1)
export dt=`/bin/date +%Y%m%d`

COUNT=1

if [ -r $1 ]; then

     /usr/bin/tail -n $2 $1 > ${PATH}${FILENAME}


     elif [ -e ${PATH}${FILENAME} ]; then

     /usr/bin/tail -n $2 $1 > ${PATH}${FILENAME}.${dt}
	
     elif [ -e ${PATH}${FILENAME}.${dt} ]; then

     /usr/bin/tail -n $2 $1 > ${PATH}${FILENAME}.${dt}.${COUNT}
			
     elif [ -e ${PATH}${FILENAME}.${dt}.${COUNT} ]; then

     COUNT=`/usr/bin/expr $COUNT + 1`

     /usr/bin/tail -n $2 $1 > ${PATH}${FILENAME}.${dt}.${COUNT}
fi

Now , all the files are getting created at once,.. .

the if condition is not working.. .

6

I figured out the script.. .

Here it is . .. Thanks !!

#!/bin/bash

#USE : ./script_name path_to_file no_of_lines
#Change the SAVEPATH where you need to save

export SAVEPATH="/home/zshaikh/"
export FILENAME=$(basename $1)
COUNT=1

if ! [ -r "$1" ]; then
    	echo "File does not exist!!"
    	exit 1
fi

if ! [ "$2" ]; then
    	echo "Specify no of lines!!!"
fi

if  ! [ -e "${SAVEPATH}${FILENAME}" ]; then
    	tail -n $2 $1 > ${SAVEPATH}${FILENAME}
    	echo "File saved at ${SAVEPATH}${FILENAME}"

elif ! [ -e "${SAVEPATH}${FILENAME}.$(date +%Y%m%d)" ]; then
    	tail -n $2 $1 > ${SAVEPATH}${FILENAME}.$(date +%Y%m%d)
    	echo "File saved at ${SAVEPATH}${FILENAME}.$(date +%Y%m%d)"

else
    	while [ -e "${SAVEPATH}${FILENAME}.$(date +%Y%m%d).${COUNT}" ]; do
            	COUNT=`expr $COUNT + 1`
    	done
    	tail -n $2 $1 > ${SAVEPATH}${FILENAME}.$(date +%Y%m%d).$COUNT
    	echo "File saved at ${SAVEPATH}${FILENAME}.$(date +%Y%m%d).$COUNT"
fi