Sponsored Content
Top Forums Shell Programming and Scripting Using sed to execute multiple commands Post 302831323 by DGPickett on Wednesday 10th of July 2013 04:51:59 PM
Old 07-10-2013
Here is a looper to remove more than one consecutive blank lines, which illustrates the concept:
Code:
sed '
  :loop
  $b
  N
  s/^\n$//
  t loop
  P
  s/.*\n//
  b loop
 '

I put my sed script on its own lines for clarity. If you want to check for lines with only spaces and tabs, that scrubbing can be done upstream in one line or inserted here as two lines. That is why I say sed loopers are usually best kept separate from non-loopers. There is no single place to filter and translate single lines in a looper without redundant processing, like substituting on each line twice.

Narrative:
  1. Create a branch target,
  2. if last line branch to end of script (print buffer and exit) as $N usually tosses the last line,
  3. get the next line on end of buffer as '\nLine_2',
  4. if both lines are empty, remove one,
  5. if line was removed branch back to loop,
  6. print the first line,
  7. remove the first line and
  8. branch back to loop.

Last edited by DGPickett; 07-10-2013 at 06:00 PM..
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

multiple sed commands

hello! I have a few sed commands sed '/^$/d' < $1 > tmp.t sed '/^ \{3,\}/d' < tmp.t > tmp1.txt ..... how can I write them in a single line? sed '/^$/d' < $1 > | '/^ \{3,\}/d' < $1 > tmp1.txt any idea? thanks. (5 Replies)
Discussion started by: george_
5 Replies

2. Shell Programming and Scripting

how do i get my script to execute multiple commands?

New to shell scripting. I can't get my script to execute multiple commands. Here's the code. It's a menu script. #!/bin/ksh clear print "SDE MENU" PS3="SDE MENU, enter choice:" select clean_menu in "tasdedev instance 5151" "orkindev instance 5155" "tasdetst instance 5157" "orkinsys... (1 Reply)
Discussion started by: hvincent
1 Replies

3. Shell Programming and Scripting

Can Xargs execute multiple commands of evry input file

Hello , I am trying to print the footer of evry file in the given directory with xargs command like follows ls -1 | xargs -I {} gzcat {} | tail -1 now problem with this is only last file foooter is getting printed as " | tail -1 " is getting executed for the last file. I know this can... (4 Replies)
Discussion started by: nilesrex
4 Replies

4. Shell Programming and Scripting

Execute multiple commands in a find

I am checking that a file is older than a reference file that I build with a touch command before processing it. If it is not old enough, I want to sleep for an hour and check again. My problem is if it is old enough to process, I want to exit when I am done, but I cannot find a way to exit... (2 Replies)
Discussion started by: prismtx
2 Replies

5. UNIX for Advanced & Expert Users

How to execute multiple unix commands in one session from java

Hi, Iam trying to code in java and wanted to run the commands in the Unix remote servers. I have the following code to run multiple GREP commands in a single session. But when i execute this, the first command executes successfully, whereas from the next line it says "Exception Occured... (1 Reply)
Discussion started by: gravi2020
1 Replies

6. UNIX for Dummies Questions & Answers

cron used to execute multiple commands

have to run multiple commands at a specified time by the user... (3 Replies)
Discussion started by: hemaa
3 Replies

7. Shell Programming and Scripting

connect to multiple servers using SSH and execute commands

Requirement: Run a shell script with below inputs file name checksum path the script should go to multiple servers (around 35) and verify the input cksum and if there is a mismatch display a simple message to the user that cksum verification failed. host details, user id /... (1 Reply)
Discussion started by: amicableperson
1 Replies

8. Shell Programming and Scripting

How to execute multiple commands in one shot?

for example: I'm greping the process where i can get the location of the file $ ps -ef | grep LLAWP | awk {'print $9'} | tail -1 /Hostname/ihs/INSTANCE2/conf/WebAgent.conf then I need to display second line of WebAgent.conf file: $ cat /Hostname/ihs/INSTANCE1/conf/WebAgent.conf | head... (2 Replies)
Discussion started by: raghur77
2 Replies

9. Shell Programming and Scripting

Ssh multiple hops to execute commands with arguments

Hi I need to write a script to ssh through several hops (e.g. HostA-HostB-HostC-HostD), where Host A does not have direct assess to HostC ; HostB cannot access HostD directly. when I ssh 3 hops and run command with arg1, arg2 and redirect the output to a file, e.g. HostA> ssh -t HostB ssh -t... (3 Replies)
Discussion started by: chiensh
3 Replies

10. UNIX for Beginners Questions & Answers

Use sed commands on multiple lines

I have a text file and i want to run 3 sed commands for the lines entered by the user using perl script. I am doing this manually till now. need some help with this The sed commands I have to use are : sed -i "s/{+//" error.txt sed -i "s/+}//" error.txt sed -i "s/\//g" error.txt... (5 Replies)
Discussion started by: utkarshkhanna44
5 Replies
GIT-STRIPSPACE(1)                                                   Git Manual                                                   GIT-STRIPSPACE(1)

NAME
git-stripspace - Remove unnecessary whitespace SYNOPSIS
git stripspace [-s | --strip-comments] git stripspace [-c | --comment-lines] DESCRIPTION
Read text, such as commit messages, notes, tags and branch descriptions, from the standard input and clean it in the manner used by Git. With no arguments, this will: o remove trailing whitespace from all lines o collapse multiple consecutive empty lines into one empty line o remove empty lines from the beginning and end of the input o add a missing to the last line if necessary. In the case where the input consists entirely of whitespace characters, no output will be produced. NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix mode of git-apply(1) for correcting whitespace of patches or files in the repository. OPTIONS
-s, --strip-comments Skip and remove all lines starting with comment character (default #). -c, --comment-lines Prepend comment character and blank to each line. Lines will automatically be terminated with a newline. On empty lines, only the comment character will be prepended. EXAMPLES
Given the following noisy input with $ indicating the end of a line: |A brief introduction $ | $ |$ |A new paragraph$ |# with a commented-out line $ |explaining lots of stuff.$ |$ |# An old paragraph, also commented-out. $ | $ |The end.$ | $ Use git stripspace with no arguments to obtain: |A brief introduction$ |$ |A new paragraph$ |# with a commented-out line$ |explaining lots of stuff.$ |$ |# An old paragraph, also commented-out.$ |$ |The end.$ Use git stripspace --strip-comments to obtain: |A brief introduction$ |$ |A new paragraph$ |explaining lots of stuff.$ |$ |The end.$ GIT
Part of the git(1) suite Git 2.17.1 10/05/2018 GIT-STRIPSPACE(1)
All times are GMT -4. The time now is 02:38 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy