CODEWITHSUNDEEP
bashshellsed
willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476709

Programmatically feed parameters to sed

Say I have a bash script, that first parses parameters/files. As a result, the script generates the following string:

args="-e 's/\\\$foo\\b/bar/gi' -e 's/\\\$baz\\b/qux/gi'"

Now I want to feed the resulting string (-e 's/\$foo\b/bar/gi' -e 's/\$baz\b/qux/gi') to sed in order to perform search and replace on for instance the following file:

Hello $foo, hello $baz

If one uses sed -e 's/\$foo\b/bar/gi' -e 's/\$baz\b/qux/gi', it returns:

Hello bar, hello qux

If however one calls:

sed $args

it gives an error:

sed: -e expression #1, char 1: unknown command: `''

How can I programmatically feed a sequence of parameters to sed?

Upvotes: 4

Views: 104

Answers (2)

user4401178
user4401178

Reputation:

You can simplify it into one string, to make it easier on the quoting: 

sedargs="s/\$foo\b/bar/gi;s/\$baz\b/qux/gi"

sed "${sedargs}" <<< "Hello \$foo, hello \$baz"

Upvotes: 1

anubhava
anubhava

Reputation: 785256

Avoid all the crazy escaping and declare args variable as a shell array:

args=(-e 's/\$foo\b/bar/gi' -e 's/\$baz\b/qux/gi')

and then use it in sed as:

s='Hello $foo, hello $baz'
echo "$s" | sed "${args[@]}"
Hello bar, hello qux

Upvotes: 2

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