Shell variables in sed when using paths

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Shell variables in sed when using paths

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By robiwan at 2010-03-22 05:13

The normal syntax for sed is:

Code:

sed "s/FINDTHIS/REPLACEBYTHIS/"

but when you have a case where REPLACEBYTHIS contains the forward slash character, that syntax will fail.

For example, say that you have a shell variable MY_LOG_PATH=/var/log/here and there is a configuration file containing a setting like

Code:

app.log.path = REALLOGPATH/log.txt

and you want to replace REALLOGPATH by the content of $MY_LOG_PATH. The incorrect approach would be

Code:

# sed -i "s/REALLOGPATH/$MY_LOG_PATH/" ./path/to/config_file

Luckily, sed accepts other separators than the forward slash, so just change the line above and use a character normally
not found in paths, such as semicolon:

Code:

# sed -i "s;REALLOGPATH;$MY_LOG_PATH;" ./path/to/config_file

and you'll be fine.

5 comments

by penguiniator on Mon, 2010-03-22 18:16

You can use nearly any character to delimit the regex and replacement text. A common replacement for / in sed expressions is #, especially when / appears in the pattern or replacement text.

by Don Johnston on Tue, 2012-11-20 09:53

I have a sed script which reads sed -e 's/@@/\xOA/g' file1 file2. It results in the file being displayed with the change. How can I have it transfer the file file with the replaced characters in place.

by sajjad008 on Tue, 2014-01-14 12:35

ok good

by vincix on Tue, 2016-08-16 17:54

Quote:

Originally Posted by Don Johnston

sed '...' file1 > file2

by Keith Hedger on Tue, 2016-08-16 19:24

Depending on your version of sed and how portable it needs to be use sed -i ... the '-i' switch stands for in place see the sed manpage for further details.

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