Comments on: Unix Sed Tutorial: Advanced Sed Substitution Examples

By: siva

siva — Mon, 14 Nov 2011 06:59:52 +0000

I am not clear about .can you explain this Grouping and Back-references in Sed.

Thanks in advance.

By: Anonymous

Anonymous — Wed, 01 Dec 2010 13:32:40 +0000

Can you please explain this Substitution.
sed -r ‘s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g’ numbers.txt

Thanks,
Rafi

By: Logan

Logan — Tue, 10 Aug 2010 22:35:12 +0000

A complete example of commify (add comma as thousands separator)

$ cat numbers.txt
1
12
123
1234
12345
123456
1234567
12345678
123456789
1234567890
1234567890.1234
+1234567890.1234
-1234567890.1234

With the “-r” option, there is no need to escape the paraenthesis and curly brackets.

The simple code below doesn’t work for numeric strings larger that 6.

$ sed -r ‘s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g’ numbers.txt
1
12
123
1,234
12,345
123,456
1234,567
12345,678
123456,789
1234567,890
1234567,890.1234
+1234567,890.1234
-1234567,890.1234

This one works. (taken from question 4.14 of http://sed.sourceforge.net/sedfaq.html)
$ sed -r ‘:a;s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g;ta’ numbers.txt
1
12
123
1,234
12,345
123,456
1,234,567
12,345,678
123,456,789
1,234,567,890
1,234,567,890.1234
+1,234,567,890.1234
-1,234,567,890.1234

By: Anjum

Anjum — Fri, 09 Apr 2010 22:10:20 +0000

Example 4 reworked and tested on Solaris 9:

echo “Welcome To The Geek Stuff” | sed ‘s/\<$[A-Z]$/$\1$/g'

Thanks,
-Anjum.

By: Anjum

Anjum — Fri, 09 Apr 2010 17:17:35 +0000

Example 5 may only work on Linux (I don’t see how) but does not work for other systems. The following snippet does work on Sun OS and am sure will work on most systems out there; including Linux:

echo ’1234
12121
3434
123′ | sed ‘s/$[0-9]\{3\}$$/,\1/g;s/^,//’

Thanks,
-Anjum.

By: Guru Prasad

Guru Prasad — Sat, 27 Feb 2010 07:40:43 +0000

Also, same is the case with example 5 as well…please let me know why

By: Guru Prasad

Guru Prasad — Sat, 27 Feb 2010 07:37:47 +0000

Hi,
Regarding the example 4, when i try it in Red Hat linux, it works, but when i try in HP-UX or SunOS it does not. Any reason why so?

By: Advanced Sed Substitution Examples - Amit Agarwal

Advanced Sed Substitution Examples - Amit Agarwal — Tue, 17 Nov 2009 03:20:30 +0000

[...] Read More: Unix Sed Tutorial: Advanced Sed Substitution Examples [...]

By: Berry

Berry — Sat, 07 Nov 2009 07:41:45 +0000

@Sasikala,

Following your tips, I found that / plus “smaller than” can match the left boundary and / plus “larger than” can match the right. Thank you again!

By: Berry

Berry — Sat, 07 Nov 2009 07:38:26 +0000

@Sasikala,

Oh, I got it. Thank you very much. ^_^

Following your tips, I found that / can match the right. Thank you again!