How do I change the output line length from the "top" linux command running in batch mode

Question

The following command is useful to capture the current processes that are taking up the most CPU and store to a file:

top -c -b -n 1 > top.log

The -c flag is particularly useful because it gives you the command line arguments of each process rather than just the process name.

Without -c:

2497 root      18   0 11264 5888 1524 S  0.0  0.1   0:03.31 miniserv.pl

With -c (additional useful command info):

2497 root      18   0 11264 5888 1524 S  0.0  0.1   0:03.31 /usr/bin/perl /usr/libexec/webmin/miniserv.pl /etc/webmin/miniserv.conf

The problem is that each line of output is truncated to fit on the current terminal window. This is ok if you can have a wide terminal because you have a lot of the output but if your terminal is only 165 characters wide, you only get 165 characters of information per process and it is often not enough characters to show the full process command. This is a particular problem when the command is executed without a terminal, for example if you do it via a cron job.

Does anyone know how to stop top truncating data or force top to display a certain number of characters per line?

This is not urgent because there is an alternative method of getting the top 10 processes ordered by CPU usage:

ps -eo pcpu,pmem,user,args | sort -r -k1 | head -n 10

Solution

You can set COLUMNS environment variable to a large value. For example, to set it just for top invocation:

$ COLUMNS=1000 top -c -b -n 1 > top.log

At least it works in bash 4.0.33 on Ubuntu 9.10.