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Full Discussion: Bash Floating point math with bc
Top Forums Shell Programming and Scripting Bash Floating point math with bc Post 302849209 by drl on Saturday 31st of August 2013 10:09:52 AM
Old 08-31-2013
Hi.

This is script s1:
Code:
#!/usr/bin/env bash

set -x
SPEED=50000
IP=8.8.8.8
s1="scale=0"
s2=$(ping -c 1 $IP  |grep rtt | cut -d'/' -f5 )
printf -v RTT "%.0f\n" $(ping -c 1 $IP  |grep rtt | cut -d'/' -f5  )

# echo ((2 * $SPEED / 8 * $RTT ))
echo $(( (2 * $SPEED) / (8 * $RTT) ))

echo or:

echo "$s1;(2*$SPEED)/(8*$s2)" | bc

when run, produces:
Code:
% ./s1
+ SPEED=50000
+ IP=8.8.8.8
+ s1=scale=0
++ ping -c 1 8.8.8.8
++ grep rtt
++ cut -d/ -f5
+ s2=48.061
++ ping -c 1 8.8.8.8
++ grep rtt
++ cut -d/ -f5
+ printf -v RTT '%.0f\n' 47.815
+ echo 260
260
+ echo or:
or:
+ echo 'scale=0;(2*50000)/(8*48.061)'
+ bc
260

Adjust parentheses as necessary. See man pages for details.

Best wshes ... cheers, drl
 

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LEARN ABOUT PHP

zgrep

ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME

       zgrep - search possibly compressed files for a regular expression

SYNOPSIS

       zgrep [ grep_options ] [ -e ] pattern filename...

DESCRIPTION

       Zgrep  invokes  grep  on  compressed  or  gzipped  files.   These  grep	options  will  cause  zgrep  to  terminate  with  an  error  code:
       (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).  All other options specified are passed directly to grep.  If no file is specified,  then  the
       standard input is decompressed if necessary and fed to grep.  Otherwise the given files are uncompressed if necessary and fed to grep.

       If the GREP environment variable is set, zgrep uses it as the grep program to be invoked.

EXIT CODE

       2 - An option that is not supported was specified.

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)

																	  ZGREP(1)
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