find and replace a path with sed?

Shell Programming and Scripting
1

Hi,

I am attempting to find the path /subject/grin* and replace it with /subject/$i
My attempt:

for i in $(ls)
do
sed -e 's:"/subjects/grin.*":"/subjects/$i.*":g'

and several variants with no luck. Please help. Thanks!

2 
sed  's/\/subject\/grin\*/\/subjects\/$i/g'
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3 
for i in $(ls)

Using ls is superfluous, this is sufficient:

for i in *
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4

Thank you so much for responding. One problem, though. It is reading $i as characters and not a variable.....

5 
sed  's/\/subject\/grin\*/\/subjects\/"'$i'"/g'

try this code ....:slight_smile:

6

Pls explain a bit more. sed needs an input stream which it does not see if used in your example's for loop; it's reading stdin instead. So sth. like ls|sed... could work on a directory, but then, what variable (i) do you want to use? I guess you need two loops on two different directories, one producing the input stream and the other the variables to replace certain parts of that stream?!

7

Hi RudiC,

the ls is actually a list of subject names that are being replaced within a parameter file that another application is dependent on. As the app processes a particular subject, the previous info is being replaced with new subject info via sed. Here is what I have, including what pamu recommended - which isn't working.

for i in $(cat list.txt)


do
sed -e 's/\/subjects\/grin\*/\/subjects\/"'i'"/g' -e "s/DDG_FL/"$i"_DDG_FL/g" -e "s/grin.*_BET_MPRAGEMoCo/"$i"_BET_MPRAGEMoCo/g" -e "s/grin.*_DDG_MC/"$i"_DDG_MC/g" L1_DDG.fsf > "$i"_DDG.fsf

feat "$i"_DDG.fsf


done

---------- Post updated at 03:00 PM ---------- Previous update was at 02:08 PM ----------

sed -e 's/\/subjects\/grin.../*\/subjects\/'$i'/g'

works......... thanks all ...

8

I don't think than anybody can follow this without representative sample input, a definitive description of the process, and matching expected output.

In this sentence, what is "it" ? Are you trying to rename the files or edit the contents of the files or what?

9

Hi methyl,

sorry for the ambiguity. What I meant by "it" was the first path. I was trying to replace a path within a text file with a different path. I could not get it to work because it involved escapes, a wildcard, and a variable. I doubt it is elegant but it seems to work now. Thanks for following up.

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