Insert text before a pattern with sed

cat some_file | sed '/pattern/i\
text to insert
' > output_file

Remove empty lines with vi

In ex mode:

:1,$s/^$//

Sometimes you need to do this too:

:1,$s/^\n//


May be able to do this:

:1,$s/^[\n$]//

Show special characters in vi

:set list

# see control chars (tabstops, control characters, etc)

Example of processing multiline records with awk

Processing multiline records is tricky. It is easier to use blank lines as record separators.


#example records
ink1 4.99
red

ink2 5.99
yellow

awk ' BEGIN { RS=""; FS=" "} { r1=$1; r2=$2; r3=$3; print "***Record***" r1 " " r2 " " r3 }' inks

#What it prints out
***Record***ink1 4.99
red
***Record***ink2 5.99
yellow

Creating a mysql user and granting privileges

//standard way of creating a user

CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';


//Creating a user and granting privileges:

GRANT ALL PRIVILEGES ON table.* TO 'user'@'localhost' identified by 'password'

//Show privileges for a user:

show grants for 'user'@'localhost'

Install Windows nic driver on Linux

#Download ndiswrapper

make #this will install the kernel module (after compiling)
modprobe ndiswrapper
ndiswrapper -i driver.inf
ndiswrapper -m #generate modprobe alias for ndiswrapper
#restart


#Check installed drivers:

ndiswrapper -l

Showing a decimal expansion with bc

#3 digits after the decimal place
echo "scale=3; 41.0 / 939.0" | bc