How to get exact number in a string with using ruby

When I search a useful code block so as to find exact number in a string, I come accross this fruitful function in Ruby:

• str.delete("^0-9.")

error: device unauthorized. Please check the confirmation dialog on your device.

While encountering this error in linux shell, you could fix it by applying below instruction

•  unplug your device
• (in shell) SDK_DIR=(android_sdk_directory)
• cd $SDK_DIR/platform_tools
• ./adb start-server
• plug device
• confirm authorization

Convert pdf to image in linux

If you look for a tool in order to convert a pdf document to a image, you could use a useful command:

convert document.pdf document.png

this little tool come in handy very much.

Quick ntfs format in Linux

sudo mkfs.ntfs -f /dev/sdb1

NTFS is a journaling file system.Hence Don't forget unmount your disk before unplugged.

qemu-timer.o: undefined reference to symbol 'timer_settime@@GLIBC_2.3.3'

Another good solution is here while compiling qemu.

../.././gcc/libgcc.mvars: No such file or directory

This bug struggled me for a long time. Therefore, I found a good solution in here.

Fruitful Regex Hints

Minimum 8 characters at least 1 Alphabet and 1 Number:

"^(?=.*[A-Za-z])(?=.*\d)[A-Za-z\d]{8,}$"
 
Minimum 8 characters at least 1 Alphabet, 1 Number and 1 Special Character:

"^(?=.*[A-Za-z])(?=.*\d)(?=.*[$@$!%*#?&])[A-Za-z\d$@$!%*#?&]{8,}$"

Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet and 1 Number:
 
"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[a-zA-Z\d]{8,}$"


Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character:

"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,}"


Minimum 8 and Maximum 10 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character:
 
"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,10}"