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chiefbag
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PostPosted: Tue Jan 29, 2013 11:10 am    Post subject: Simple sed problem [SOLVED] Reply with quote

For some reason I am having issues trying to execute a simple sed command.
What I'm trying to do is insert a line into a file after a line of a certain pattern

From the dev manual http://devmanual.gentoo.org/tools-reference/sed/index.html it gives the below example however it does not appear to work.

Anyone know what I am doing wrong or is there an easier way to do this?

The command executes without error but file remains as is.

Created a file with the following:

Code:

itest
To:


Command I run

Code:
sed -i -e '/^To: $/a    Bob' data.in


From the stat command I can see that sed must be attempting some change to the file.

Code:

stat data.in
  File: 'data.in'
  Size: 11              Blocks: 8          IO Block: 4096   regular file
Device: 803h/2051d      Inode: 8001109     Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/ XXX)   Gid: ( 1000/ XXX)
Access: 2013-01-29 11:08:25.875020840 +0000
Modify: 2013-01-29 11:08:25.875020840 +0000
Change: 2013-01-29 11:08:25.875020840 +0000
 Birth: -

$ sed -i -e '/^To: $/a    Bob' data.in


 $ stat data.in
  File: 'data.in'
  Size: 11              Blocks: 8          IO Block: 4096   regular file
Device: 803h/2051d      Inode: 8001108     Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/ XXX)   Gid: ( 1000/ XXX)
Access: 2013-01-29 11:08:44.505020914 +0000
Modify: 2013-01-29 11:08:44.505020914 +0000
Change: 2013-01-29 11:08:44.505020914 +0000
 Birth: -

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Last edited by chiefbag on Tue Jan 29, 2013 11:29 am; edited 1 time in total
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tomk
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PostPosted: Tue Jan 29, 2013 11:21 am    Post subject: Re: Simple sed problem Reply with quote

chiefbag wrote:
Code:

itest
To:


There is no space after the To: so the regex doesn't match, if you change it to the following it works:

Code:
sed -i -e '/^To:$/a    Bob' data.in

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chiefbag
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PostPosted: Tue Jan 29, 2013 11:28 am    Post subject: Reply with quote

Thanks :)

I should have continued reading the info:

Code:
Basic Atoms
Atom    Purpose
text    Literal text
\( \)    Grouping
\|    Alternation, a or b
* \? \+ \{\}    Repeats, see below
.    Any single character
^    Start of line
$    End of line
[abc0-9]    Any one of
[^abc0-9]    Any one character except
[[:alpha:]]    POSIX character class, see below
\1 .. \9    Backreference
\x (any special character)    Match character literally
\x (normal characters)    Shortcut, see below

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mv
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PostPosted: Tue Jan 29, 2013 11:34 am    Post subject: Re: Simple sed problem [SOLVED] Reply with quote

chiefbag wrote:
Code:
sed -i -e '/^To: $/a    Bob' data.in

You require an exact match (start of line, "T", "o", ":", " ", end of line). I suppose in your file the space (" ") before he end of the line is missing, and so the test fails for all of your lines.
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