how to modify the text in file

i am using a file say file1.txt . in that file i am refering to files like xxx1.data etc. in all the occurences i want to append this string as $testname/xxx1.data( preceed the xxx1.data with $testname. here $testname is a variable name which is having some value and has been set earlier and i m using its value by calling the scalar). now what i had tried actually replaces the xxx1.data , i do not want to delete the string only add new text before it. Thanks sachin

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Re: how to modify the text in file by Thilosophy (Curate) on Jan 19, 2005 at 07:07 UTC
now what i had tried actually replaces the xxx1.data , i do not want to delete the string only add new text before it. What have you tried? Show us some code... If you tried `s[\w\w\w1\.data][$testname/]g` [download] you might consider `s[(\w\w\w1\.data)][$testname/$1]g` [download] instead. The `$1` stands for the text enclosed in the first set of round brackets in the pattern.	[reply] [d/l] [select]
Re^2: how to modify the text in file by sachin_chat (Initiate) on Jan 19, 2005 at 07:19 UTC
i was using something like perl -npi.bak -e "s:(\w\d+\.data):testname/$1:g" file1.txt . it actually repleces the text and do not do what i wanted	[reply]
Re^3: how to modify the text in file by dse (Novice) on Jan 19, 2005 at 07:31 UTC
First, you need to replace "\w\d+" with "\w+\d+". Otherwise, your regex is only going to match "x1.data" instead of "xxx1.data". Second, I assume you're using bash, sh, or a similar shell on a Unix box. When passing arguments using double-quotation marks, you need to escape any backslashes, dollar signs, and certain other characters. I recommend using single-quotation marks instead since most characters don't have to be escaped inside them. Suggestion: perl -npi.bak -e 's:(\w+\d+\.data):testname/$1:g' file1.txt	[reply]
Re^3: how to modify the text in file by Thilosophy (Curate) on Jan 19, 2005 at 07:30 UTC
Aha ! `perl -npi.bak -e "s:(\w\d+\.data):testname/$1:g" file1.txt` [download] That is a shell quoting problem. Your $1 gets replaced by an (empty) environment variable before Perl sees it. Use single quotes: `perl -npi.bak -e 's:(\w\d+\.data):testname/$1:g' file1.txt` [download]	[reply] [d/l] [select]