use some part of variable value to replace ../../ values in a file

Shell Programming and Scripting
1

hi,

i have variable value as follows

val="/dir1/dir2/dir3/dir4/dir5/dir6/file1"

it is pointing to some file location.

and i have another file as

../../dir4/file3
../../dir4/dir5/file4
../../dir7/file5

i want the output as

/dir1/dir2/dir3/dir4/file3
/dir1/dir2/dir3/dir4/dir5/file4
/dir1/dir2/dir3/dir7/file5

please anybody help me.

2

If I got your purpose right, you may try this:

sed "s|^\.\./\.\.|$(echo "$val"|cut -c 1-15)|g" <filename>

What would be your required output if one of the lines in the file was

../../dir5/file5

????

/dir1/dir2/dir3/dir5/file5

OR

/dir1/dir2/dir3/dir4/dir5/file5

?

3

for example i wrote the directories names as dir1, dir2 and so on.

those directories names are different.

i need the script for different directory names but no.of directories to be replaced is 3 as

if variable is val="/dir1/dir2/dir3/dir4/dir5/dir6/file1" then i have to replace ../../ with /dir1/dir2/dir3/

if variable is val="/home/gopu/india/dir4/dir5/dir6/file1" then i have to replace ../../ with /home/gopu/india/

4

Then try

sed "s|^\.\./\.\.|$(echo "$val"|cut -d/ -f1-4)|g" <filename>
5

it's working fine . thank you elixir_sinari

6

I always worry about marking relative references in scripts. If something doesn't exist, a cd will just refuse and unless you carefully manage errors, then you could end up damaging important files. Consider:-

cd /etc
grep -v bankhost hosts > dr_test_hosts
cd /disaster
rm *
cp -pR /etc/* .

This would (probably in a bad way anyway) remove a sensitive remote host address from /etc/hosts in preparation for a DR test to reduce the risk of actually sending data to the bank. Of course, if you run this and /disaster does not exist then you empty /etc, which could be a little awkward, to say the least.

Could it be a better plan to have a variable made of several others, such as:

maindir=/dir1/dir2
val=${maindir}/dir3/dir4/file1
...do something...
val=${maindir}/dir3/newdir4/file2
...do something...
val=${maindir}/dir3/bigdir4/file3
...do something...

You would still have to check that these exist, of course, but it reduces the risk of a typing error and one action compounding on another.

Maybe I'm paranoid, but unless you consider every possible action and error, then it's a dangerous game. I've been bitten in the past, so I can't claim perfection, just learning from experience.

I hope that this helps,
Robin
Liverpool/Blackburn
UK

7

one small thing elixir_sinari

if in the file there are morethan ../../ values like ../../../ or ../../../../

then how to modify the sed command. i tried as follows but it is not working

sed "s|^(\.\./)* | $(echo "$val"|cut -d/ -f1-4)|g" filename
8

Something on these lines...

sed -n "s|^\(\.\./\)\{2\}|$(echo "$val"|cut -d/ -f1-4)/|gp" <filename>

Just change the value in the interval regular expression....the number in boldface...