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| == How can i perform a substitution (s/foo/bar/) safely, without treating either value as a regular expression? == | == How can i perform a substitution with arbitrary values ("s/$foo/$bar/") safely, without treating either value as a regular expression or worrying about other special characters? == |
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| Sed is not the right tool for this. At best, it will be an escaping nightmare, and extremely prone to bugs. First, what are we performing the substitution on? If it's a string, it can be done very simply with a parameter expansion. {{{ var='some string' echo "${var//some/another}" }}} This is discussed in more detail in [[BashFAQ/100][Faq #100]]. If it's a file or stream, things get a bit trickier. One way to accomplish this would be to combine the previous method with [[BashFAQ/001][Faq #1]]. {{{ # file while IFS= read -r line; do printf '%s\n' "${line//foo/bar}" done < file # command output while IFS= read -r line; do printf '%s\n' "${line//foo/bar}" done < <(my_command) my_command | while IFS= read -r line; do printf '%s\n' "${line//foo/bar}" done }}} The second of the two command examples there creates a subshell. See [[BashFAQ/024][Faq #24]] for more information on that. Both of the above examples print to stdout. Neither actually edits the file in place. Of course this could be resolved with something like: {{{ while IFS= read -r line; do printf '%s\n' "${line//foo/bar}" done < file > new_file && mv new_file file }}} |
This FAQ has been merged with [[BashFAQ/021|Faq #21]]. |
How can i perform a substitution with arbitrary values ("s/$foo/$bar/") safely, without treating either value as a regular expression or worrying about other special characters?
This FAQ has been merged with Faq #21.