CODEWITHSUNDEEP
bashsed
jonny b
jonny b

Reputation: 75

Why won't my sed command work with double quotes?

I am using the following command to delete all text before a match in a file:

sed -n '/sweet/,$p' file

It works perfectly, but i need to change 'sweet' to a variable, as its a variable i assume i need to use double quotes instead of single quotes, however when i run this command:

sed -n "/$variable/,$p" file

i receive the following error:

sed: -e expression #1, char 11: unexpected `,'

How can i make this command work?

Upvotes: 1

Views: 3532

Answers (2)

Ondrej K.
Ondrej K.

Reputation: 9679

Single quotes tell shell to not perform any expansion at all and sed gets three arguments -n, /sweet/,$p, and file.

When using double quotes, variables get expanded. Presuming variable=sweet and p not being set, second sed call got the following three arguments: -n, /sweet/,, and file. Address specifier where , is not followed by anything is not valid and gave you the error you've seen.

If you want to mix a (literal) $ and variable expansion in a single argument, you have few option:

  • "/$variable/,\$p" which escapes the $
  • "/$variable/"',$p' or similar mix of single and double quoted string parts to treat $ in each of its segment as needed.

Upvotes: 4

lw0v0wl
lw0v0wl

Reputation: 674

I would brake the single quote for use a double for the variable then reopen the single quote.

sed -n '/'"${var}"'/,$p' file

I know this is working, however I not really used it yet so I don't know if this is the right way to do this.

Upvotes: 1

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