Explained shell statement

Posted by Mats Stijlaart on Stack Overflow See other posts from Stack Overflow or by Mats Stijlaart
Published on 2011-02-16T15:15:51Z Indexed on 2011/02/16 15:25 UTC
Read the original article Hit count: 228

Filed under:

shell

|

sed

|

io

|

cat

The following statement will remove line numbers in a txt file:

cat withLineNumbers.txt | sed 's/^.......//' >> withoutLineNumbers.txt

The input file is created with the following statement (this one i understand):

nl -ba input.txt >> withLineNumbers.txt

I know the functionality of cat and i know the output is written to the 'withoutLineNumbers.txt' file. But the part of '| sed 's/^.......//'' is not really clear to me.

Thanks for your time.

© Stack Overflow or respective owner

Related posts about shell

How to restrict the users' shell allowing to execute shell programs

as seen on Server Fault - Search for 'Server Fault'
Is it possible to prevent any user to not use commands like ls, rm and other system commands which could harm the system. But the users should be able to execute shell programs. >>> More
Shell extension installation not recognized by Windows 7 64-bit shell

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a Copy Hook Handler shell extension that I'm trying to install on Windows 7 64-bit. The shell extension DLL is compiled in two separate versions for 32-bit and 64-bit Windows. The DLL implements DLLRegisterServer which adds the necessary registry entries. After adding the registry entries… >>> More
Running shell commands without a shell window

as seen on Stack Overflow - Search for 'Stack Overflow'
With either subprocess.call or subprocess.Popen, executing a shell command makes a shell window quicky appear and disappear. How can I run the shell command without the shell window? >>> More
Why can't I reinstall MySQL?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I've been looking all around the Internet for an answer but didn't find anything. I hope you can help me now. I have a server with MySQL. From one day to another, MySQL didn't let me enter with my root password anymore (accsess denied for user 'root'@'localhost' using password: 'YES'). So I tried… >>> More
Bash/shell script - shell output redirection inside a function

as seen on Stack Overflow - Search for 'Stack Overflow'
function grabSourceFile { cd /tmp/lmpsource wget $1 > $LOG baseName=$(basename $1) tar -xvf $baseName > $LOG cd $baseName } When I call this function The captured output is not going to the log file. The output redirection works fine until I call the… >>> More

Related posts about sed

sed + RE , want to ignore remarked line using sed

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to replace the a string with the word string as the following example down , but if a string exist also after comment then a string will replaced too In which way I can add to the sed command the irregular exp that ignore from the #. [root@localhost tmp]# more test a b aa bb #a #b #aa #bb [root@localhost… >>> More
script to search and replace deprecated functions

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am using the following script to search and replace the deprecated functions in a file with the newer ones. 5 for strFile in `ls deprecated_functions_search_and_replace.txt ` 6 do 7 sed "s/ereg_replace[^\(]*(\([^,]*\),/preg_replace\1('#'.\2.'#',/g" $strFile > temp_file 8 … >>> More
Footer not stretching 100% when horizontally scrolled

as seen on Pro Webmasters - Search for 'Pro Webmasters'
I have a footer which is set to 100% width, but if i size the window smaller so a horizontal scrollbar appears, using the scrollbar shows whitespace to the right of the footer ... its not spanned 100% of the page, just the viewport. <!doctype html> <html lang="en" class="no-js"> <head> … >>> More
What does this regex mean and why

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
$ sed "s/\(^[a-z,0-9]*\)\(.*\)\( [a-z,0-9]*$\)/\1\2 \1/g" desired_file_name I apreciate it even if you only explain part of it or at lest structure it with words as in s\alphanumerical_at_start\something\alphanumerical_at_end\something_else\global Could someone explain what that means, why and… >>> More
Sed problem in a Bash script

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
Hello there. I'm having a problem using the sed command . I'm trying to write a bash script that does the following : search for the line that contain :@ then save the line that contained :@ and replace it with new line as in the following: #! /bin/bash echo "Please enter the ip address… >>> More