Shell Programming and Scripting

Post a sample file you're trying to edit. Please use code tags.

Code:

$ ruby -ne '$_="##{$_}" if /xyz/; print' file

Hi,
Please find the sample content of the file. Purpose is to comment all the hotbackup scripts that are scheduled in the cron. This is just a sample, there are 85 databases.

$ crontab -l

Code:

05 02 * * 1-6  /xyz/hotbackup.sh >> /xyz/log/hotbackup.log
45 03 * * 1-6  /xyz/netbackup.sh DAILY
10 02 * * 1-6  /xyz/hotbackup.sh >> /xyz/log/hotbackup.log
10 03 * * 0    /xyz/coldbackup.sh >> /xyz/log/coldbackup.log

Moderator's Comments:

Please use code tags when posting data and code samples!

Please provide the appropriate information!

Hi,
Please find the sample content of the file. Purpose is to insert # at the start of line wherever it finds word hotbackup through strem editor.

Contents in file:

Code:

05 02 * * 1-6  /xyz/hotbackup.sh >> /xyz/log/hotbackup.log
45 03 * * 1-6  /xyz/netbackup.sh DAILY
10 02 * * 1-6  /xyz/hotbackup.sh >> /xyz/log/hotbackup.log
10 03 * * 0    /xyz/coldbackup.sh >> /xyz/log/coldbackup.log

This is to be expected and the reason for that behavior is simple: sed will not modify the file it is reading from, because doing so would destroy the data you want to change in first place.

Interactive editors can change files in place, because they create a copy of the original file and work on this copy *), then overwrite the original version with the edited one. sed on the other hand works in a stream (as its name suggests) and therefore can't use a copy.

If you want to replace a file with its edited version do the following:

Code:

# sed '<your-sed-commands-here>' /path/to/source > /path/to/newfile
# mv /path/to/newfile /path/to/source

I hope this helps.

bakunin

*) For example, this is why "vi" cannot edit files bigger than the available space in /var/tmp. "vi" will use /var/tmp to store the copy and if it can't it will refuse to open the file.

Code:

printf '/hotbackup/s!^!#!g\nwq!\n' | ex -s myFile
OR
{ rm myFile; sed -e '/hotbackup/s!^!#!' > myFile; } < myFile