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blaCkninJa
Asked: 2017-02-23 01:42:01 +0800 CST

Unable to replace path using sed

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How can i replace a path with another path in file using sed command, And when it is used as a variable in script it is working.

sed -i "s/"system_filter = /etc/define_filter_file"/"system_filter = /usr/local/etc/file_regex"/g" /etc/exi.conf.bak

sed

2 Answers

  1. Best Answer

    You need to escape all slahes in the provided paths and change opening and terminating quotes to single quotes.

    sed -i 's/"system_filter = \/etc\/define_filter_file"/"system_filter = \/usr\/local\/etc\/file_regex"/g' /etc/exi.conf.bak

    The command is expressed as:

    sed -i 's/path1/path2/g'

    Path1 and path2 can not clearly contains / as this will be confused with the whole expression.

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  2. From the infotex manual of GNU sed (see info sed):

    The syntax of the s (as in substitute) command is s/REGEXP/REPLACEMENT/FLAGS. The / characters may be uniformly replaced by any other single character1 within any given s command. The / character (or whatever other character is used in its stead) can appear in the REGEXP or REPLACEMENT only if it is preceded by a \ character.

    i.e. use | as the delimiter between the REGEXP and the replacement and the sed command becomes:

    sed -i 's|"system_filter = /etc/define_filter_file"|"system_filter = /usr/local/etc/file_regex"|g' /etc/exi.conf.bak

    or in short: 

    sed s|/some/path|/alternate/path/|

    which is much easier than the alternative, escaping a large number of forward slashes: 

    sed s/\/some\/path/\/alternate\/path\//

    1.(The sed man page on OSX explicitly excludes the backslash \ and newline characters from the above qualification of "any other single character" )

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