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I have a csh script (although I can change languages if it has any relevance) where I have to:

sed s/AAA/BBB/ file

The problem is that AAA and BBB are paths, and so contain '/'. AAA is fixed, so I can say:

sed s/\\\/A\\\/A\\\A/BBB/ file

However, BBB is based on variables, including $PWD. How do I escape the '/' in $PWD?

OR is there some other way I should be doing this entirely?

Jonathan Leffler
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Brian Postow
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7 Answers7

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sed can use any separator instead of / in the s command. Just use something that is not encountered in your paths:

s+AAA+BBB+

and so on.

Alternatively (and if you don't want to guess), you can pre-process your path with sed to escape the slashes:

pwdesc=$(echo $PWD | sed 's_/_\\/_g')

and then do what you need with $pwdesc.

Jonathan Leffler
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Lev Levitsky
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    Interesting. I never knew that '/' wasn't actually PART of sed... everyone seems to use it by default, so I just assumed it was mandatory. thanks. – Brian Postow Aug 24 '12 at 14:40
  • @LevLevitsky : Just a question :`\b`match a word but what match a path? This is because I want to append a path before a file name and I want to avoid to do it twice. – user2284570 Aug 10 '14 at 14:04
  • @user2284570 Not sure I understand the question. `\b` matches a word boundary, btw. Maybe you should try asking a new question (or searching for existing ones)? – Lev Levitsky Aug 10 '14 at 14:12
  • I have `"crti.o`or `$(crti.o)`I need to apend `/var/path/`before them, but the sed command is called several times so it become `"/var/path//var/path//var/path//var/path/crti.o`or `$(/var/path//var/path/crti.o)`. – user2284570 Aug 10 '14 at 14:59
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    @user2284570 Then you probably want to match the name as something not starting with a slash: `\b[^\/]\w*`, or similar. But I don't see a direct connection with my answer that we are commenting on right now. – Lev Levitsky Aug 10 '14 at 15:06
  • That's still related to `How to replace a path with another path in sed`. – user2284570 Aug 10 '14 at 15:47
  • this got to be one of the most valuable bits of knowledge Ive ever absorbed. – The Fool Aug 16 '21 at 17:11
48

In circumstances where the replacement string or pattern string contain slashes, you can make use of the fact that GNU sed allows an alternative delimiter for the substitute command. Common choices for the delimiter are the pipe character | or the hash # - the best choice of delimiting character will often depend on the type of file being processed. In your case you can try

sed -i 's#/path/to/AAA#/path/to/BBB#g' your_file

Note: The g after last # is to change all occurrences in file if you want to change first ouccurence do not use g

c0m3t
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19
sed -i "s|$fileWithPath|HAHA|g" file

EDIT 1

sed -i 's|path/to/foo|path/to/bar|g' file
pylover
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8

Using csh for serious scripting is usually not recommended. However, that is tangential to the issue at hand.

You're probably after something like:

sed -e "s=$oldpath=$newpath="

where the shell variable $oldpath contains the value to be replaced and $newpath contains the replacement, and it is assumed that neither variable contains an equals sign. That is, you're allowed to choose the delimiter on pattern, and avoiding the usual / delimiter avoids problems with slashes in pathnames. If you think = might appear in your file names, choose something less likely to appear, such as control-A or control-G.

Jonathan Leffler
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  • This isn't serious scripting... (it's not strictly comical either, but it's only 43 lines, including whitespace and comments...) You're right, If it was much longer, I'd turn it into python. – Brian Postow Aug 24 '12 at 14:39
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In my case the below method works.

sed -i 's/playstation/PS4/' input.txt

Can be also be written as

sed -i 's+playstation+PS4+' input.txt

  • sed : is stream editor

  • -i : Allows to edit the source file

  • +: Is delimiter.

I hope the above information works for you .

vijayraj34
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1

We just needed to get the /h/ network path references out of the path. if we pointed them back to the /c/ drive they would map to non-existant directories but resolve quickly. In my .bashrc I used

PATH=`echo $PATH | sed -e "s+/h/+/c/+g"`
D M Lowe
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0

You can use parenthesis expansion ${i/p/r} to escape the slashes. In this case ${i//p/r} for escaping all occurrences.

$p1=${p1//\//\\/}
$p2=${p2//\//\\/}
sed s/$p1/$p2/ file

Or, more concise, in one line sed s/${p1//\//\\/}/${p2//\//\\/}/ file

The two fist slashes // are a separator in parenthesis expansion saying we are matching all occurrences, then \/ is for escaping the slash in the search template, the / as a second separator in the expansion, and then \\/ is the replacement, in witch the backslash must be escaped.

FrViPofm
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