Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Reading a single character from each line of the file
Top Forums Shell Programming and Scripting Reading a single character from each line of the file Post 302479646 by ripat on Sunday 12th of December 2010 04:12:57 AM
Old 12-12-2010
If your input file is large you might benefit from using awk. It will be faster. Considerably faster if you have mawk on your box.

Tested on a infile with 13000 lines:
Code:
$ time ./read_line_do.sh infile > /dev/null
real	0m18.873s
user	0m18.285s
sys	0m0.580s

$ time gawk '{print substr($0,25,1)}' infile > /dev/null
real	0m3.884s
user	0m3.860s
sys	0m0.024s

$ time original-awk '{print substr($0,25,1)}' f > /dev/null
real	0m1.244s
user	0m1.224s
sys	0m0.020s

$ time mawk '{print substr($0,25,1)}' infile > /dev/null
real	0m0.111s
user	0m0.084s
sys	0m0.028s

By the way, the original awk seems to be faster than gawk this time! But it can't beat the lightning fast mawk.
 

10 More Discussions You Might Find Interesting

1. Programming

reading a single character in C

Can anyone help me????? My problem is that i want to read only one charcter from keyboard. Each time my program waits to press enter or ^d. I don't want that. As soon as i press a charcter it should proceed to next statement in program without pressing enter or ^d. please help... (3 Replies)
Discussion started by: alodha
3 Replies

2. Shell Programming and Scripting

reading a single line

hello, i need an algorithm which reads a line specified to it in shortest possible time. i am already using sed, i need a better way. please suggest me alternatives (2 Replies)
Discussion started by: rochitsharma
2 Replies

3. Shell Programming and Scripting

Reading Multiple Variables From a Single Line in Shell

I'm a Linux newb, I've been running a Debian Linux server for about a year now, and I've written some simple scripts to automate various things, but I still don't know much, and I forget what I learn as fast as I figure it out... Anyway, that really isn't important, I just want you to know that... (14 Replies)
Discussion started by: Drek
14 Replies

4. UNIX for Dummies Questions & Answers

Trying to remove single character from a line

Here is a sample code grep '903' -i user.txt | tail -2 | awk '{print $2}' | sed 's/B//g' the input file has data as such 903-xxx-xxxxB 903-xxx-xxxxB It is a dialer file i want to remove the "B" any help thanks (5 Replies)
Discussion started by: Iz3k34l
5 Replies

5. Shell Programming and Scripting

Looking for a single line to count how many times one character occurs in a word...

I've been looking on the internet, and haven't found anything simple enough to use in my code. All I want to do is count how many times "-" occurs in a string of characters (as a package name). It seems it should be very simple, and shouldn't require more than one line to accomplish. And this is... (2 Replies)
Discussion started by: Shingoshi
2 Replies

6. Shell Programming and Scripting

[Solved] Problem in reading a file line by line till it reaches a white line

So, I want to read line-by-line a text file with unknown number of files.... So: a=1 b=1 while ; do b=`sed -n '$ap' test` a=`expr $a + 1` $here do something with b etc done the problem is that sed does not seem to recognise the $a, even when trying sed -n ' $a p' So, I cannot read... (3 Replies)
Discussion started by: hakermania
3 Replies

7. HP-UX

How to remove new line character and append new line character in a file?

Hi Experts, I have data coming in 4 columns and there are new line characters \n in between the data. I need to remove the new line characters in the middle of the row and keep the \n character at the end of the line. File is comma (,) seperated. Eg: ID,Client ,SNo,Rank 37,Airtel \n... (8 Replies)
Discussion started by: sasikari
8 Replies

8. Shell Programming and Scripting

How to avoid the truncating of multiple spaces into a single space while reading a line from a file?

consider the small piece of code while read line do echo $line done < example content of example file sadasdasdasdsa erwerewrwr ergdgdfgf rgerg erwererwr the output is like sadasdasdasdsa erwerewrwr ergdgdfgf rgerg erwererwr the... (4 Replies)
Discussion started by: Kesavan
4 Replies

9. Shell Programming and Scripting

Reading of variable in a single line command

Hi All, Below is a sample command that I can run without any problem in the command line. Command Line dtToday=`date +%Y%m%d`; ls -ltr ./filename_${dtToday}.txt -rw-r--r-- 1 monuser oinstall 0 Jan 18 11:02 ./filename_20130118.txt But once I put that command line in file (list.txt) and... (3 Replies)
Discussion started by: padi
3 Replies

10. Shell Programming and Scripting

How to understand special character for line reading in bash shell?

I am still learning shell scripting. Recently I see a function for read configuration. But some of special character make me confused. I checked online to find answer. It was not successful. I post the code here to consult with expert or guru to get better understanding on these special characters... (3 Replies)
Discussion started by: duke0001
3 Replies

LEARN ABOUT SUNOS

ppmtosixel

ppmtosixel(1)						      General Commands Manual						     ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.	The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
	      pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order	of  magni-
	      tude larger than a compressed file and prints much slower.

       -margin
	      If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
	      fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater	than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

								   26 April 1991						     ppmtosixel(1)
All times are GMT -4. The time now is 02:19 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy