Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: How to replace all but the first 3 characters with sed?
Top Forums Shell Programming and Scripting How to replace all but the first 3 characters with sed? Post 302934793 by Scrutinizer on Tuesday 10th of February 2015 09:37:49 PM
Old 02-10-2015
Quote:
Originally Posted by DGPickett
I hate sed loops for one byte change per loop, so you can split the lines and then rejoin them[..]
Quote:
Originally Posted by RudiC
Point taken! I don't really like pipe organs, so tried a no loop no pipe solution[..]
Did a small test and indeed, those 1 character loops are expensive.
It turns the awk solutions appear to be fastest.
Code:
$ time sed -e :a -e 's/\(...\)[^*]/\1*/;ta' file > /dev/null

real	0m0.114s
user	0m0.110s
sys	0m0.003s

$ time { sed '
  s/^.\{0,3\}/&\
/
' file | sed '
  $q
  N
  P
  s/.*\n//
  s/./*/g
'|sed '
  $q
  N
  s/\n//
' ;} > /dev/null

real	0m0.015s
user	0m0.015s
sys	0m0.006s

$ time sed 'h;s/\(...\).*/\1/;x;s/^...//;s/./*/g;H;x;s/\n//' file > /dev/null

real	0m0.018s
user	0m0.013s
sys	0m0.002s

$ time perl -pe 's/(?<=...)./*/g' file >/dev/null

real	0m0.030s
user	0m0.022s
sys	0m0.005s

$ time awk '{x=substr($0,N+1); gsub(".","*",x); print substr($0,1,N) x}' N=3 file > /dev/null

real	0m0.010s
user	0m0.007s
sys	0m0.002s

$ time gsed "s/./*/4g" file > /dev/null

real	0m0.022s
user	0m0.018s
sys	0m0.002s

time awk -F'^...' '{a=$2; gsub(/./,"*",a); print substr($0,1,3) a}' file > /dev/null

real	0m0.009s
user	0m0.006s
sys	0m0.003s

Last edited by Scrutinizer; 02-10-2015 at 11:13 PM.. Reason: Some sed/awk times were GNU sed/awk, rather than BSD sed/awk. Correct it
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

how to replace control characters using sed?

How can I use sed to replace a ctrl character such as 'new line' (\0a) to something else? Or any other good command can do this job? Thanks, Hillxy (5 Replies)
Discussion started by: hillxy
5 Replies

2. Shell Programming and Scripting

Sed replace characters not equal to an expression

Hi all, Suppose I have a file with the contents below, and I only want to print words %S_ then | sort -u. ------------------------------ The %S_MSG that starts with '%.*s' is too long. Maximum length is %d. The %S_MSG name '%.*s' contains more than the maximum number of prefixes. The... (5 Replies)
Discussion started by: poldo
5 Replies

3. Shell Programming and Scripting

Using sed to replace special characters

Hi everyone I have file1 contains: '7832' ' 8765 6543 I want a sed command that will format as: '7832' , '8765' , '6543' I tried sed -e s/\'//g -e 's/^*//;s/*$//' file1 > file2 sed -e :a -e '$!N; s/\n/ /; ta' file2 which gives: 7832 8765 6543 I need some help to continue with... (5 Replies)
Discussion started by: nimo
5 Replies

4. Shell Programming and Scripting

Bash: using SED, trying to replace some characters except first or last line

Hi, I require to replace 2 items: 1. replace start of all lines in a file with ' except the first line 2. replace end of all lines in a file with '||chr( except last line I am able to do the entire file using sed -e s/^/\'/g -e s/$/\'\|\|chr\(/g "$file" > newfile.txt but am not yet able... (0 Replies)
Discussion started by: Chella15
0 Replies

5. UNIX for Dummies Questions & Answers

Bash: using SED, trying to replace some characters except first or last line

Hi, I require to replace 2 items: 1. replace start of all lines in a file with ' except the first line 2. replace end of all lines in a file with '||chr( except last line I am able to do the entire file using sed -e s/^/\'/g -e s/$/\'\|\|chr\(/g "$file" > newfile.txt but am not yet... (3 Replies)
Discussion started by: Chella15
3 Replies

6. Shell Programming and Scripting

sed replace range of characters in each line

Hi, I'm trying to replace a range of characters by their position in each line by spaces. I need to replace characters 95 to 145 by spaces in each line. i tried below but it doesn't work sed -r "s/^(.{94})(.{51})/\ /" inputfile.txt > outputfile.txt can someone please help me... (3 Replies)
Discussion started by: Kevin Tivoli
3 Replies

7. Shell Programming and Scripting

Replace characters infile with sed

I have several files in a directory that look like this: jacket-n r potential-n - outcome-n f reputation-n b I want to replace the characters in the second column with certain numbers. For instance, I want the letters 'f', 'r' and 'b' in the second column to replaced with 0 and I want the... (1 Reply)
Discussion started by: owwow14
1 Replies

8. Shell Programming and Scripting

sed replace nth characters with string

Hi, I hope you can help me out please? I need to replace from character 8-16 with AAAAAAAA and the rest should stay the same after character 16 gtwrhtrd11111111rjytwyejtyjejetjyetgeaEHT wrehrhw22222222hytekutkyukrylryilruilrGEQTH hrwjyety33333333gtrhwrjrgkreglqeriugn;RUGNEURGU ... (4 Replies)
Discussion started by: stinkefisch
4 Replies

9. Shell Programming and Scripting

sed replace characters using a wildcard

Hello, I have some data that looks like the following, > <SALTDATA> (OVS0199262) HCl > <IDNUMBER> (OVS0199262) OVS0199262 > <SUPPLIER> (OVS0199262) TimTec > <EMAIL> (OVS0199262) info@timtec.net > <WEBSITE> (OVS0199262) http://www.timtec.net I need to remove the data in... (3 Replies)
Discussion started by: LMHmedchem
3 Replies

10. Shell Programming and Scripting

sed command on AIX, replace specific characters

Hi, Im using sed on an AIX machine. I am trying to change the 137-139 characters if they are a ' 36'/'000' to a '036'. The positions that need to be changed are fixed. the source data that I have is$cat v.txt 4000422985400050462239065593606500000007422985707771046154054910075641MC0318AMWAY... (9 Replies)
Discussion started by: dsid
9 Replies

LEARN ABOUT LINUX

times

TIMES(P)						     POSIX Programmer's Manual							  TIMES(P)

NAME

       times - write process times

SYNOPSIS

       times

DESCRIPTION

       The  times  utility  shall  write  the accumulated user and system times for the shell and for all of its child processes, in the following
       POSIX locale format:

	      "%dm%fs %dm%fs
%dm%fs %dm%fs
", <shell user minutes>,
		  <shell user seconds>, <shell system minutes>,
		  <shell system seconds>, <children user minutes>,
		  <children user seconds>, <children system minutes>,
		  <children system seconds>

       The four pairs of times shall correspond to the members of the <sys/times.h> tms structure (defined  in	the  Base  Definitions	volume	of
       IEEE Std 1003.1-2001, Chapter 13, Headers) as returned by times(): tms_utime, tms_stime, tms_cutime, and tms_cstime, respectively.

OPTIONS

       None.

OPERANDS

       None.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       None.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       See the DESCRIPTION.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       Zero.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       None.

EXAMPLES

	      $ times
	      0m0.43s 0m1.11s
	      8m44.18s 1m43.23s

RATIONALE

       The times special built-in from the Single UNIX Specification is now required for all conforming shells.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Special Built-In Utilities

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								  TIMES(P)
All times are GMT -4. The time now is 08:40 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy