put string on top of the text

packets · 07-28-2010, 07:42 PM

I want to create a script wherein it will put a string somewhere on the text file. But my priority was on top but I hope I can place it in any lines if possible. I tried to create a script using redirect ">" and then put it on top of the file.

The text contains:

Quote:

foo
fee
fii
fuu

I want to put "MY TEXT" so I did the script below:

Code:

#!/bin/bash

cat /root/tmp/text > /root/tmp/text.tmp
echo "MY TEXT" > /root/tmp/text
cat /root/tmp/text.tmp >> /root/tmp/text
rm -f /root/tmp/text.tmp

Is there other way I could do this?

paulsm4 · 07-28-2010, 09:36 PM

Looks good to me

Minor variation:

Code:

echo "MY TEXT" > tmp
cat myfile >> tmp
mv tmp myfile

PS:
Always try to use "root" as SELDOM as possible (ideally, NEVER log on and NEVER do any serious activity as root).

ghostdog74 · 07-28-2010, 09:41 PM

Code:

sed '1 i text' file #insert at line 1
sed '10 i text' file #insert at line 10
awk 'NR==1{print "text"}1 ' file  # insert at line 1
awk 'NR==10{print "text"}1 ' file  # insert at line 10

packets · 07-28-2010, 09:42 PM

@paulsm4

Quote:

echo "MY TEXT" > tmp
cat myfile >> tmp
mv tmp myfile

Thanks. Much lesser code much better

About the root thing. Thanks for the reminder :-)

packets · 07-28-2010, 09:44 PM

@ghostdog74

Thanks for this. Will try this one. I truly appreciate all your replies. I notice you're the only one who usually replies to my questions. Thanks for the LWQ Community.

Quote:

sed '1 i text' file #insert at line 1
sed '10 i text' file #insert at line 10
awk 'NR==1{print "text"}1 ' file # insert at line 1
awk 'NR==10{print "text"}1 ' file # insert at line 10

tonyfreeman · 07-28-2010, 10:33 PM

Well ... this is not as elegant but I was bored and put this together:

Code:

#!/bin/bash

INSERT=0
INFILE=infile.txt
OUTFILE=outfile.txt
TEXT=""

function usage () {
cat << EOF

usage: $0 options

  -n   Number of lines into your file to enter text.  Default = 0 (top)
  -i   The file containing your text list. Default = infile.txt
  -t   [Mandatory] The text inside quotes that will be inserted at line 'n' inside file 'i'.
  -o   The file created by this script with the result of inserting 
       your test at line 'n' inside 'i' file. Default is outfile.txt

EOF
exit 0
}

function my_exit () {
	cat $OUTFILE
	exit
}

while getopts "hn:i:o:t:" flag
do
	case $flag in
	n)
		if [[ $OPTARG -gt 0 ]]
		then
			INSERT=$(expr $OPTARG - 1)
		else
			INSERT=$OPTARG
		fi
		;;
	i)
		if [[ -f $OPTARG ]]
		then
			INFILE=$OPTARG
		else
			echo "WARNING: infile does not exist.  Using infile.txt instead"
			echo -e "dummy \ndummy \ndummy" > infile.txt
		fi
		;;
	o)
		OUTFILE=$OPTARG
		if [[ -f $OPTARG ]]
		then
			echo "WARNING: outfile $OUTFILE exists.  Will overwrite."
		fi
		;;
	t)
		TEXT=$OPTARG
		;;
	h)
		usage
		;;
	\?)
		usage
		;;
	*)
		usage
		;;
	esac
done


if [ "x" == "x$TEXT" ]
then
	echo "-t  option is mandatory ... so enter some text in quotes"
	exit
fi


if [[ ! -f $INFILE ]]
then
	echo "WARNING: infile does not exist.  Using infile.txt instead"
	echo -e "dummy \ndummy \ndummy" > infile.txt
fi


TEMPFILE="blah.txt.$$"

if [[ $INSERT -eq 0 ]]
then
	echo "$TEXT" > $TEMPFILE
	cat $INFILE >> $TEMPFILE
	mv $TEMPFILE $OUTFILE
	my_exit
fi

TOTAL=$(cat $INFILE | wc -l)
HEAD=$INSERT

if [[ $HEAD -gt $TOTAL ]]
then
	cat $INFILE > $TEMPFILE
	echo "$TEXT" >> $TEMPFILE
	mv $TEMPFILE $OUTFILE
	my_exit
fi

TAIL=$(expr $TOTAL - $INSERT)

head -n $HEAD $INFILE > $TEMPFILE
echo "$TEXT" >> $TEMPFILE
tail -n $TAIL $INFILE >> $TEMPFILE
mv $TEMPFILE $OUTFILE
my_exit

Now run the program like this:

Code:

./test.sh -n 2 -t "hello there old man"

You should get this output:

Code:

tony@monarch:~$ ./test.sh -n 2 -t "hello there old man"
dummy 
hello there old man
dummy 
dummy

The text 'hello there old man' is placed at line #2 as specified by the -n switch in the output file ... and you will have infile.txt and outfile.txt on your system.

packets · 07-29-2010, 12:06 AM

@tonyfreeman

Thanks for this sample script.