nitesh8860

#!/bin/bash
echo script name: $0
echo first argument: $1
echo number of arguments passed:  $#
echo all the arguments are: $@
echo exit status of most recent process: $?
echo process id of the script: $$
echo username: $USER
echo hostname: $HOSTNAME
echo a random number: $RANDOM

nitesh8860

# Note that spaces cannot be used around the `=` assignment operator
whom_variable="World"
# Use printf to safely output the data
printf "Hello, %s\n" "$whom_variable"
> Hello, World


#If you want to bash to expand your argument, you can use Weak Quoting:
#!/usr/bin/env bash
world="World"

nitesh8860

#add below to ~/.bashrc

force_color_prompt=yes
color_prompt=yes
parse_git_branch() {
         git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/(\1)/'
 }
 if [ "$color_prompt" = yes ]; then
          PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[01;31m\]$(parse_git_branch)\[\033[00m\]\$ '
  else

nitesh8860

    max_arr=max(arr)
    arr=list(filter(lambda x: x!=max_arr, arr))
    print(max(arr))

nitesh8860

def fun(s):
    # return True if s is a valid email, else return False
    import re
    rex = re.compile("^[\w\-\_]+\@[a-zA-Z0-9]+\.\w{1,3}$")
    if rex.match(s):
        return True
    else:
        return False

nitesh8860

from functools import reduce       
l=[1,2,3,4]
print(reduce(lambda x,y: x*y, l, -1))
#> -24

#reduce(func with 2 params, iterable, initial value )

nitesh8860

from datetime import datetime
t1='Sat 02 May 2015 19:54:36 +0530'
t2='Fri 01 May 2015 13:54:36 -0000'
t1=datetime.strptime(t1,'%a %d %b %Y %H:%M:%S %z')
t2=datetime.strptime(t2,'%a %d %b %Y %H:%M:%S %z')

# print(t1-t2)
#> 1 day, 0:30:00

print ((t1-t2).total_seconds())

nitesh8860

# List comprehensions are the fastest.

def test1():
    l = []
    for i in range(1000):
        l = l + [i]

def test2():
    l = []
    for i in range(1000):

nitesh8860

export AWS_DEFAULT_REGION=eu-west-1

aws logs describe-log-groups --query 'logGroups[*].logGroupName' --output table | \
awk '{print $2}' | grep ^/aws/rds | while read x; do  echo "deleting $x" ; aws logs delete-log-group --log-group-name $x; done

nitesh8860

#to print column number:
STDIN | awk '{print $COLUMN_NUMBER}'