script for reading file or stream

I often wanted to pass the file to a pipeline some command, and also if the file is parameter to command it should accept


Voila!!

here is 'stream.sh'

#!/bin/bash

file=${1:--}

cat $file 

Usage and output

$ ./stream.sh underSTANDING.txt 

If you understand, say "understand".

If you don't understand, say "don't understand".

But if you understand and say "don't understand".

How do I understand that you understand? Understand!

$ cat underSTANDING.txt | ./stream.sh 

If you understand, say "understand".

If you don't understand, say "don't understand".

But if you understand and say "don't understand".

How do I understand that you understand? Understand!

$ ./stream.sh < underSTANDING.txt 

If you understand, say "understand".

If you don't understand, say "don't understand".

But if you understand and say "don't understand".

How do I understand that you understand? Understand!

bytes to gb/tb conversion

Often had to go to websites to do the bytes to KB.. TB.. GB conversions
here is the quick script for handy use

#!/bin/bash

# Give numeric value, which is in bytes

# will show all possible conversions 

call_bc() {

n1=$1

n2=$2

echo "scale=4; $n1/($n2)" |bc

}

nm=$1

pw=$2

pn=""

k_ilo=1024;

m_ega=$k_ilo*$k_ilo;

g_iga=$m_ega*$k_ilo;

t_era=$g_iga*$k_ilo;

p_eta=$t_era*$k_ilo;

[ -z "$nm" ] && exit

echo  "B: "$nm

for i in K M G T P; do

case $i in

K)pn=$k_ilo;;

M) let pn=$m_ega;;

G) let pn=$g_iga;;

T) let pn=$t_era;;

P) let pn=$p_eta;;

esac

echo -n "$i: "; call_bc $nm $pn

done

Usage and output

$ ./convert.sh 74274576

B: 74274576

K: 72533.7656

M: 70.8337

G: .0691

T: 0

P: 0

 

Creating date range for next few hours

We often get cases when we need date ranges to be generated, so it can take care of hours, days, months properly.

Script: file dategen.sh

#!/bin/bash
_g_DT="$1"
_g_TM="$2"

_DT=`date -d "$_g_DT $_g_TM" +"%Y%m%d %H"`

echo "For: $_DT"

for i in `seq 0 5`; do
      _DT_gen=`date -d "$_DT +$i hours" +"%Y-%m-%dT%H:00"`
      echo -e "\t$_DT_gen"
done

E.g with Sep 30, at 23 hours

bash dategen.sh "2014-09-30" "23"


For: 20140930 23
 2014-09-30T23:00
 2014-10-01T00:00
 2014-10-01T01:00
 2014-10-01T02:00
 2014-10-01T03:00
 2014-10-01T04:00

check how old is the file

Hi,

we often need to check, how old is the file from the current date

$ export  FILE="the-big-file.log" ; echo `date +"%s"` - `stat -c %Z $FILE`|bc


this command gives us the difference in secs; how old is the file (the-big-file.log)

Getting the odd lines

Hi, if you have to display only the odd lines from the file we can try
let file
$ cat myfile.txt
1
2
3
4
5
6
7
8
9

$ sed -ne '1~2p' myfile.txt
1
3
5
7
9

$ awk '{if (NR%2==1) {print;} }' myfile.txt
1
3
5
7
9

Scatter Gather on linux

Hi,

I have been doing this many times but never blogged, its the scatter gather use to be on dbase days;

This program:
$ cat hello.sh
source e/big.conf

set `date` && export WeekDay=$1 Month=$2 Day=$3 Time=$4 Year=$6

echo Hello $NAME
echo $NO
echo Time: $Time
echo Date: $WeekDay $Month $Day $Year


$ sh hello.sh
Hello SmaLl
2000
Time: 11:24:29
Date: Fri Oct 14 2011

In hello.sh, i am calling the name/value pairs file,
$ cat e/big.conf

NAME=SmaLl

NO=2000

Exporting the date o/p to the positional parameters, hey did it in college days.
set `date` && export WeekDay=$1 Month=$2 Day=$3 Time=$4 Year=$6

Here we can have large name value pairs from static file or runtime command and play with it.

more on date and old date

Hi,

I had to work with epoch dates, that was older than the current, struggled a bit.
check this,

#!/bin/bash

dt1=`date`
dt2=`date -d "$dt 1 hour ago"`

s1=`date -d "$dt1" +"%s"`
s2=`date -d "$dt2" +"%s"`

echo Now - $dt1
echo
echo "1 Hour Before   -- $dt2 : $s2"
echo "Now             -- $dt1 : $s1"

put whatever for 1 hour ago as (ago for old, just 1 hour for future, you can have day, minutes)

change dt1 for any date, here its current can be date by -d option


PS:
check good examples in the info pages, i checked this late.. :(
$info date examples