topic Challenging Script question in Operating System - Linux

Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 11:20:18 GMT

I have a file named File1 with the following data:
Line1
Line2
Line3
Line4
Line5

Im trying to write a script that takes two arguments. The first being a line of text and the second the name of the file above. How do I insert the first argument(line of text) into the first line of the file named above.

For example:

./scriptTest Hello this is a test File1

Would append File1 as such:
Hello this is a test
Line1
Line2
Line3
Line4
Line5

Re: Challenging Script question

Mel Burslan — Tue, 18 Apr 2006 11:25:08 GMT

header=$1
filename=$2
(echo $header ;cat $filename) > /tmp/mytmpfile
mv /tmp/mytmpfile $filename

one of the ways how to do it..

HTH

Re: Challenging Script question

Mel Burslan — Tue, 18 Apr 2006 11:26:11 GMT

forgot to add, if your comment is multiple words containing spaces, make sure to enclose it in quotes.

Re: Challenging Script question

Pete Randall — Tue, 18 Apr 2006 11:26:21 GMT

You're going to have to put quotes around the "Hello this is a test", then your script will look like:

echo $1 > /tmp/file
cat $2 >> /tmp/file
cp /tmp/file $2

Pete

Re: Challenging Script question

James R. Ferguson — Tue, 18 Apr 2006 11:32:02 GMT

Hi:

Using the shell only:

cat ./insertit
#!/usr/bin/sh
echo "${1}" >> "${2}.new"
cat ${2} >> "${2}.new"
mv "${2}.new" "${2}"

# ./insert it ok yourfile

Regards!

...JRF...

Re: Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 11:47:54 GMT

Hi is there any other way to do it without having to use quotes. I cant say to the user if you have more than one word then put quotes around it.

So far I have managed the following.

sed -e '1i\' -e "$*" > File1

But this appends the whole line including the second argument.

Re: Challenging Script question

Rodney Hills — Tue, 18 Apr 2006 12:00:39 GMT

Can you have the users put the filename first, then-

f=$1
t=/tmp/hold$$
shift
echo $* | cat - $f >$t
mv $t $f

HTH

-- Rod Hills

Re: Challenging Script question

Sandman! — Tue, 18 Apr 2006 12:01:36 GMT

How about the following:

echo hello this is a test file1 | awk '{
for(i=1;i $NF
}'

cheers!

Re: Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 12:03:52 GMT

Hi

The line of text has to come first then the file name.

Thank you

Re: Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 12:10:05 GMT

Hi Sandman

Im not sure that will work. How does the script know to echo the line of text: Hello this is a test, unless you manually type it in the script.

It could be any line of text.

Re: Challenging Script question

Sandman! — Tue, 18 Apr 2006 12:10:31 GMT

Infact to build a shell script do the following:

=================myshellscript=================
#!/bin/sh

echo $* | awk '{
for(i=1;i $NF
}'
=============================================

Give your script a name "myshellscript" make it executable "chmod" and execute it at the command line as...

# ./myshellscript

hope it helps!

Re: Challenging Script question

Kent Ostby — Tue, 18 Apr 2006 12:12:04 GMT

You can do it without quotes like this:

given file1
Line1
Line2
Line3
Line4
Line5

./script Hello world file1

script:
touch .mytempx
rm .mytemp?*
echo $@ | awk '{print "cp ", $NF, " .mytempfile2" }' > .mytempx
echo $@ | awk '{print "cat ", " .mytempfile2 >> .mytempfile3"; print " mv .mytempfile3 ",$NF }' > .mytempx2
chmod +x .mytempx .mytempx2
./.mytempx
echo $@ | awk '{$1==$NF="";print $0}' > .mytempfile3
./.mytempx2

Re: Challenging Script question

Sandman! — Tue, 18 Apr 2006 12:20:45 GMT

In my last post I forgot to add that run the shell script you created as follows:

# myshellscript Hello this is a test file1

...passing command line arguments to the script instead of running it w/o any.

cheers!

Re: Challenging Script question

James R. Ferguson — Tue, 18 Apr 2006 12:29:15 GMT

Hi:

Here's yet another way to offer the user the ability to specify the name of the file *last* and the string to insert *first* without the need to quote anything:

# cat .inject.pl
#!/usr/bin/perl
my $file = pop;
open(FH,"<",$file) or die "Can't open $file\n";
print "@ARGV\n";
print while ();
1;

For example:

# ./inject.pl Hello this is a test FileName

Regards!

...JRF...

Re: Challenging Script question

Rodney Hills — Tue, 18 Apr 2006 12:29:43 GMT

Here is a method that uses ksh arrays to pick off the last argument.

set -A a $*
(( n = ${#a[*]} - 1 ))
f=${a[$n]}
a[$n]=""
t=/tmp/hold$$
echo ${a[*]} | cat - $f >$t
mv $t $f

HTH

-- Rod Hills

Re: Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 12:59:51 GMT

Hi Sandman

Just tried your code but it seems to delete everything in the file and then write the line of text to the file.

Any ideas?

Re: Challenging Script question

James R. Ferguson — Tue, 18 Apr 2006 13:27:42 GMT

Hi:

If you prefer not to preserve your original file, but use the Perl script I suggested, then use this version:

# cat .inject.pl
#!/usr/bin/perl
my $oldfile = pop;
my $newfile = "$oldfile.new";
open(FIN, "<",$oldfile) or die "Can't open '$oldfile': $!\n";
open(FOUT,">",$newfile) or die "Can't open '$newfile': $!\n";
print FOUT "@ARGV\n";
print FOUT while ();
close FOUT;
close FIN;
rename($newfile, $oldfile);
1;

For example:

# ./inject.pl Hello this is a test FileName

In this variation, the modified file ("FileName") is updated, "in-place".

Regards!

...JRF...

Re: Challenging Script question

Sandman! — Tue, 18 Apr 2006 13:35:48 GMT

>Just tried your code but it seems to delete >everything in the file and then write the >line of text to the file.

>Any ideas?

Here's the updated version of "myshellscript" so that file1 doesn't get clobbered and the text gets written above the first line in file1:

=============================================
#!/bin/sh -x

echo $@ | awk '{
system("mv "$NF" tmpfile1")
for(i=1;i $NF
system("cat tmpfile1 >>"$NF)
}'
=============================================

hope it helps!

Re: Challenging Script question

Unix or Linux? — Tue, 18 Apr 2006 13:47:46 GMT

Hi Sandman

It worked perfectly. Thank you.
Any chance that you could explain the code as it is a bit advanced for me.

Re: Challenging Script question

Sandman! — Tue, 18 Apr 2006 13:50:54 GMT

The shell script is attached so that its clearer to follow. Moreover you can use $* and $@ interchangeably.

cheers!