Replacing character in file with null value

HLee1981 · #1 (**permalink**) 06-16-2006

What is the null value's character to replace in the following syntax?
---
Command: cat filename | tr "charactertoreplace" "nullvalue" > newfilename
===
After googling, searching in this forum, and asking local in-house programmers regarding the question, the closest I got to was just simply "null" (without the quotes, i.e.
---
cat afilename | tr "\n" null > newafilename
===
However, that did not do the same thing that GUI-based editors like Textpad, and UltraEdit does. Is there a way to achieve this task that can be scripted when wanting to apply the action to multiple files? Please assist.

Thanks!

jim mcnamara · #2 (**permalink**) 06-16-2006

Code:

tr -s '\n' '\000' < oldfile > newfile

vgersh99 · #3 (**permalink**) 06-16-2006

are you trying to substitute with the ASCII 'NUL'? [I'm not sure]

if that's the case 'tr' can take octal representations:

Quote:

Originally Posted by man tr

\octal A backslash followed by 1, 2 or 3 octal digits represents a
character with that encoded value. To follow an octal
sequence with a digit as a character, left zero-pad the octal
sequence to the full 3 octal digits.

'NUL' in octal is '000'.

tr '\n' '\000' < afilename >newafilename

HLee1981 · #4 (**permalink**) 06-26-2006

Quote:

Originally Posted by vgersh99

are you trying to substitute with the ASCII 'NUL'? [I'm not sure]

if that's the case 'tr' can take octal representations:

'NUL' in octal is '000'.

tr '\n' '\000' < afilename >newafilename

Thanks! Works like a charm. Would octal representations handle replacing values like ^M, ^U, etc.? I'm trying to replace ^U at the moment with a newline character, but can't seem to find out how to specify the "^U" in the tr -s command. Where can I find a list of the special characters and their corresponding values for such tasks?

vgersh99 · #5 (**permalink**) 06-26-2006

try 'man ascii'

HLee1981 · #6 (**permalink**) 06-26-2006

Quote:

Originally Posted by vgersh99

try 'man ascii'

Thanks! Because I'm seeing the phrase ^N when I view the file with the less command, and the octal values for ^ and N are respectively 136 and 116, how would I combine the two to have it replaced by a '\n'?

vgersh99 · #7 (**permalink**) 06-26-2006

Code:

$ echo '^N' | od -c
0000000  016  \n
0000002

for '^N':

Code:

tr '\016' '\000' < afilename >newafilename

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Replacing a character string in a file	rjsha1	Shell Programming and Scripting	13	04-11-2009 01:07 PM
Null Character Handling	npk2210	Shell Programming and Scripting	3	09-29-2007 04:51 AM
replacing the character "\" in a file	rjsha1	Shell Programming and Scripting	5	01-11-2006 09:45 AM
Find files which contain a null character	Bab00shka	UNIX for Dummies Questions & Answers	5	12-16-2005 10:41 AM
sending a null character to a terminal	vertigo23	UNIX for Advanced & Expert Users	3	09-30-2005 09:58 PM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by