How to add a text to first line of a text file?
 

Hello! I need to add a line to text files. Basically, I need to add "<pre>" tag to the first line of text files to make them viewable on web browsers. I guess I could create a file with "<pre>" tag on it first and then concatenate the text file to it. But this needs to be done to hundreds of text files every morning. And I was wondering if there is a way that will take less time and cpu power. Thanks for your input!

for example, a text file could be...

apples
oranges
bananas
pears

I need to change this to...
<pre>
apples
oranges
bananas
pears

Ah, kill me, I've no idea. I'd probably do it this way:But that's pretty much what you're trying to avoid.. Huh. Is it really THAT much of a CPU eater?

You can try with sed, inserting the string before the first line of the file and by editing the file in place with option -i

cron job
 

If it needs to be done every morning then create a shell script with any of the previously mentioned solutions that work for you, and install it as a cron job.

I wouldn't call such a routine a CPU eater. Not even for a few hundred files. The script could finish the job within seconds. I do not assume you have 100MB text files to display in a web browser.

Server issues

Thanks for all your replies! It seems that a solution with echo command combine all lines to a one line. Is there a way to get around this?

$echo '<pre>' . `cat fruits` > myfruits
$cat fruits
apples
oranges
bananas
pears
$cat myfruits
<pre> . apples oranges bananas pears
$


With sed solution, I get a long error message as shown below.
$sed -i 1i"<pre>" fruits
sed: invalid option -- i
Usage: sed [OPTION]... {script-only-if-no-other-script} [input-file]...

-n, --quiet, --silent
suppress automatic printing of pattern space
-e script, --expression=script
add the script to the commands to be executed
-f script-file, --file=script-file
add the contents of script-file to the commands to be executed
--help display this help and exit
-V, --version output version information and exit

If no -e, --expression, -f, or --file option is given, then the first
non-option argument is taken as the sed script to interpret. All
remaining arguments are names of input files; if no input files are
specified, then the standard input is read.

E-mail bug reports to: bug-gnu-utils@gnu.org .
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.

If your sed doesn't have the -i option, then just do it explicitly. As you suggested, just create a file with '<pre>' then cat the other file onto it. This is *no* easier way to do it, you can't prepend data onto a file without rewriting it.

Do NOT use `cat ...`, this is completely retarded, you're cat'ing the file to stdout, then echoing it back to the file, thus taking twice as long as it should (maybe Maligree works for MS? ;)).

if its showing in a webpage you could create a php page to do it for you.


<?php include("textfile.php"); ?>

I think it will work with .txt files as well. and <pre> tag could be included in the main page.

You could also get fancy with the shell script like

#!/bin/bash
for i in $(cat *.txt);
do
echo "<pre>" >> page.htm
echo "$i" >> page.htm
done
exit

I have not written a shell script for a long time so the above may be completely wrong, but its an idea.

Shell script would be the best if these files are going to be changing daily.