square brackets

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1. Shell Programming and Scripting

IF statement with square brackets

Hi All, Hope you all are doing good. Yesterday in my project i came across a scenario which i can not guess why it was working in one region and why it was not in another region. Please find my issue below. I am using AIX version 6.0 of UNIX in my project, in shell scripting i have the...

2. Shell Programming and Scripting

Problem with occurence of square brackets

Hello all, I have the following problem: $ cat infile this is spam and i need this too this is spam and i need this too $ perl -nwe '$_ =~ /]+ \]+)\]\]*\]? (\+)$/; print "$1 - $2\n";' infile i need this - too i need this - and i need this too I am not sure how many occurences of...

3. Shell Programming and Scripting

Grep number between Square [] brackets

I wanted to store the number inside the square bracket between colon( : ) and closing suqre bracket(]) in some variable. Suppose I have lines like : Input file : 20140320 00:08:23.846 INFO 84] - anything in line 20140320 00:08:23.846 Test 589] - Virtual and lab lab anything...

4. Shell Programming and Scripting

Compare the value in between square brackets in file

I wanted to compare the value inside the Squre bracket after Colon ( : ) based on any value(seperated by or operator | ) inside the variable Thread and if match found then wnated to store in output file Input file : 20140320 00:08:43.918 INO 35] - Corporate hub is 20140320 00:08:43.918...

5. Shell Programming and Scripting

Delete text between square brackets and also delete those square brackets using sed or awk

Hi All, I have a text file which looks like this: computer programming systems engineering I want to get rid of these square brackets and also the text that is inside these brackets. So that my final text file looks like this: computer programming systems engineering I am using...

6. Shell Programming and Scripting

Replacing text between two square brackets

hi guys, i'm writing a script that looks for a unquie id in a file and replaces a string between two square brackets on the same line as the unquie id: ....... ....... 0001 zz 43242 replace this text] name 0002 sd 65466 UK] country ....... ....... how can i find line with id 0001...

7. UNIX for Dummies Questions & Answers

Test command - Two square brackets

Hello, Can someone please explain to me the following line, ] && break I do not understand why two test square brackets are used. Thanks, Shantanu ---------- Post updated at 03:38 PM ---------- Previous update was at 03:35 PM ---------- And, also why there's a $ before (echo $c |...

8. Shell Programming and Scripting

Double square brackets question

Hi, I just came across an interesting shell script syntax like the one below: ] && (trap 'rm -rf ${WORK_DIR}/*.$$; echo "\n\nInterrupted !!\n\n"; exit 4' 1 2 3 15) Can someone please explain the code snippet above? The trap command bit is fine but ] && is the hazy part. Generally we use an...

9. Shell Programming and Scripting

Use of double square brackets in ksh

Hi First apologies if this has been raised before. I've got the following in a ksh script: if ] For some reason this does not work. But if I remove the double square brackets to: if This works. I thought ksh supported the ]. Or is there more to it? Thanks in advance.

10. Shell Programming and Scripting

WHy the double square brackets?

One of the senior administrators gave me a shell script to modify and it begins as follows: if ] && ] {more code follows} Why the double square brackets?

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pnmpsnr

pnmpsnr(1)						      General Commands Manual							pnmpsnr(1)

NAME

       pnmpsnr - compute the difference between two images (the PSNR)

SYNOPSIS

       pnmpsnr [pnmfile1] [pnmfile2]

DESCRIPTION

       Reads  two  PBM,  PGM, or PPM files, or PAM equivalents, as input.  Prints the peak signal-to-noise ratio (PSNR) difference between the two
       images.	This metric is typically used in image compression papers to rate the distortion between original and decoded image.

       If the inputs are PBM or PGM, pnmpsnr prints the PSNR of the luminance only.  Otherwise, it prints the separate PSNRs of the luminance, and
       chrominance (Cb and Cr) components of the colors.

       The  PSNR  of  a  given component is the ratio of the mean square difference of the component for the two images to the maximum mean square
       difference that can exist betwee any two images.  It is expressed as a decibel value.

       The mean square difference of a component for two images is the mean square difference of the component value, comparing  each  pixel  with
       the pixel in the same position of the other image.  For the purposes of this computation, components are normalized to the scale [0..1].

       The maximum mean square difference is identically 1.

       So the higher the PSNR, the closer the images are.  A luminance PSNR of 20 means the mean square difference of the luminances of the pixels
       is 100 times less than the maximum possible difference, i.e. 0.01.

SEE ALSO

       pnm(5)

								   04 March 2001							pnmpsnr(1)

UNIX for Dummies Questions & Answers