greptastic flavorites

greptastic_flavorites

# display a random number based on the number of lines in a file
echo $(($RANDOM%`grep -c '$' ~/.bash_history`))

# replace COMMAND to find all the libboost libraries it is using
lsof | grep 'COMMAND.*mem.*libboost'

# display contents of file without comments or empty lines, also removes "in-line" comments
# this is an example of a reason to NOT USE IN LINE COMMENTS
egrep -v '#|^$' /etc/mysql/my.cnf

# display file contents without leading comments or empty line, preserves "in line" comments
egrep -v '^#|^$' /etc/mysql/my.cnf

# display the content of multiple files, without empty lines, preserving "in line" comments
egrep -hv '^#|^$' /var/log/*.log

# output the total ram available
# Example: 8176 MB of RAM
echo "$(( $(egrep -o "MemTotal:[[:space:]]+[[:digit:]]+[[:space:]]" /proc/meminfo | awk '{print $2}') / 1000 )) MB of RAM"

# return total physical processors
grep "physical id" /proc/cpuinfo | sort -u | wc -l

# return cores per cpu
grep "cpu cores" /proc/cpuinfo |sort -u |cut -d":" -f2

# return total logical cores 
grep -c "processor" /proc/cpuinfo

# Match valid IPv4 addresses
$ grep -E -o "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)" file.txt

# display all files in pwd and below that do not contain the pattern chewbacca
# output: ./dirname/filename
find . -type f \! -exec grep -q 'chewbacca' {} \; -print

# test command success after execution, instead of using $?
if $(grep -q 'chewbacca' file);
  then
    echo 'file does contain "chewbacca"'
  else
    echo 'file does not contain the "chewbacca"'
fi