bash howto's

first line:

#!/bin/bash

#input parameters count:

$#

#script parameters:

$0 - self name, $1 ... $9 - input params

#check that file exist, the spaces near "[" and "]" are required :

if [ -e "streamcount.info" ]

then

echo 'file exist info'

fi

#get file extension:

SHORTFILENAME=$(basename $FULLFILENAME)

DEST_EXT=${SHORTFILENAME##*.}

#get temporary file name:

TFILE="/tmp/streaminfo.$RANDOM.$$.tmp"

#working directory:

$PWD

#redirect error stream to console and filter strings that contain word "Stream":

ffmpeg -i "$SRC" 2>&1 | grep "Stream"

#count strings with grep -c and put it into variable:

a=$( cat < $TFILE | grep -c "Audio:" )

#save command result as array with ( $( ) ):

s=( $( cat < $TFILE | grep "Audio:" | cut -f 2 -d "#" | cut -f 1 -d "(" ) )

#print array contents:

echo "stream numbers: ${s[@]:0}"

#use "for" construction:

for i in `seq 2 $a`;

do

index=$( echo "$i-1" | bc )

v="${s[index]}"

echo "$i. $v"

done

#extract float value:

x=$( echo "qwerty: 123.123123 !" | sed "s/.*[^0-9]\([0-9]\.[0-9]*\).*/\1/g" )

#float point operations:

echo "(256 / $x) / 10" | bc

for float result:

bc -l

# Checks for root privileges

if [ "$(whoami)" != 'root' ]

then

echo "You need to be root to execute uphosts. Exiting!"

exit 1

fi

# Checks required packages

ABORT=0

builtin type -P wget &>/dev/null || { echo -n "wget is missing."; ABORT=1; }

builtin type -P unzip &>/dev/null || { echo -n "unzip is missing."; ABORT=1; }

builtin type -P fromdos &>/dev/null || { echo -n "fromdos(tofrodos) is missing."; ABORT=1; }

builtin type -P grep &>/dev/null || { echo -n "grep is missing."; ABORT=1; }

if [ $ABORT != 0 ]

then

echo " Exiting!"

exit 2

fi