Using sed with special characters

I have a directory full of XML files that look like this, for which I want to change the value of the “offset” element number from 1 to some other number

$ cat my.xml
      <offset xmlns="">1</offset>

I wrote various combinations of this sed command, but nothing I tried runs without an error. I am pretty sure that I need to escape some of the characters, but those that I’ve tried always end in errors (“unexpected token”, “unknown option”, etc). I also tried without the -e flag, since it really isn’t an expression.

sed -i -e s/<offset xmlns="">1</offset>/<offset xmlns="">99</offset>/ *.xml

Any help would be appreciated.

Answers:

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Method 1

You don’t need to use / in sed, you can use comma for example:

sed -i 's,<offset xmlns="">1</offset>,NEW_TEXT,' FILE

Method 2

Try this,

$ sed 's~<offset xmlns="">1~<offset xmlns="">99~g' file
          <offset xmlns="">99</offset>

Use a different sed delimiter if the input contain slashes.

Method 3

You don’t usually need all of that in the s/earch/replace/ function itself, and can instead first /address/ then conditionally /s///. It can not only help with readablity and to avoid some of the issues you mention, there can be a performance increase as well:

sed '/offset xmlns=/s/>1</>99</'

Method 4

Use a proper parser for XML files. For example, I’d use xsh and use the following script:

for my $file in { @ARGV } {
    open $file ;
    for //offset set . 1 ;
    save :b ;
}

Method 5

I would replace the 17th character of the line, which contains the value:

sed -i 's/^(.{17})./1VALUE/' file.xml

Replace VALUE with the new value for <offset>. Eg.

sed -i 's/^(.{17})./18/' file.xml

to change it to 8.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0