useful bash commands

useful.sh

# how-to-clean-log-file (http://unix.stackexchange.com/questions/92384/how-to-clean-log-file)
> logfile
cat /dev/null > logfile
dd if=/dev/null of=logfile
truncate logfile --size 0

# how to get a file octal permissions
stat -c "%a"

# check a makefile for tabs and line endings
# it shows the presence of tabs with ^I and line endings with $ both are vital to ensure that dependencies end properly and 
# tabs mark the action for the rules so that they are easily identifiable to the make utility.....
cat -e -t -v  makefile_name