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Old 04-22-2008, 03:55 PM   #1
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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...


I need to change this to...
Old 04-22-2008, 04:08 PM   #2
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Ah, kill me, I've no idea. I'd probably do it this way:
echo '<pre>'.`cat your_file` > your_file
But that's pretty much what you're trying to avoid.. Huh. Is it really THAT much of a CPU eater?

Last edited by Maligree; 04-22-2008 at 04:12 PM.
Old 04-22-2008, 04:13 PM   #3
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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
sed -i 1i"<pre>" filename
Old 04-22-2008, 09:05 PM   #4
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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

Last edited by marquardl; 05-01-2008 at 05:08 AM.
Old 04-23-2008, 11:42 AM   #5
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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
$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: .
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.
Old 04-23-2008, 12:29 PM   #6
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sed: invalid option -- i
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? ).

Last edited by ararus; 04-23-2008 at 12:32 PM.
Old 04-23-2008, 01:40 PM   #7
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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

for i in $(cat *.txt);
echo "<pre>" >> page.htm
echo "$i" >> page.htm

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.

Last edited by jei; 04-23-2008 at 01:43 PM.


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