pattern matching

Shell Programming and Scripting
1

hi ,

i am trying to search for a pattern in the file and then replace the pattern.

please guide me

Thanks,
Mahi

2

man grep
man sed

3

hi pludi,

i tried with sed cmd

sed 's/ABC/abc/g' $file1

but i can see the change only on cmd prompt but the in the file ABC is not replaced with abc.

4

u need to redirect it to anoter file, u cannot directly make changes in original file. U can use replace command in VI editor if you want...

Ex: sed s/ABC/abc/g $file >$file_tmp

U can use replace command in VI editor if you want...

syntax: :%s/ABC/abc/g (in vi editor)

5

sed tries to be non-destructive, so it will keep your input untouched and print any changes to STDOUT. If you want to change a file inplace, try

cp ${file1} ${file1}.orig
sed -e 's/ABC/abc/g' ${file1}.orig > ${file1}
rm ${file1}.orig
6

thanks for the help ..
but i have a small problem here
actually i need to create a new file with a name similar to the old file.

i.e. if the old file is abc.txt , the new file should be abc_1.txt
i should get the substring of the file name and then name the new one
please let me know how to do it

Thanks in Advance

7

So you don't want to change the content of the file, but the filename. I can give you 2 options for that:

  1. If all files have the same extension use basename ${file} <ext> (e.g. basename ${file} '.txt'), which will give you the filename without the extension
  2. If they use different extensions use echo ${file} | sed -e 's/\(.*\)\.\(.*$\)/\1_1.\2/', which will append '_1' to the filename
8

i tried with ur solutions but i am unable to get it

if my file name is in $file variable and i need the file name with out the extension in one variable and the extension in another variable.
how do i do it

please help me ..