Concatenation in shell script and use of 'basename' - bash

Question

I want to read all file names form a particular directory and then create new files with those names by appending some string to them in another directory.
e.g > 'A', 'B', 'C' are in 'logs' directory
then script should create 'A_tmp', 'B_tmp', 'C_tmp' in 'tmp' directory
what i am using is -
tempDir=./tmp/
logDir=./logs/
for file in $( find `echo $logDir` -type f )
do
name=eval basename $file
echo $name
name=$(echo $name | sed 's/.$//')
echo $tempDir
opFile=$tempDir$name
echo $opFile
done
But what I understood is, $file is containing '\n' as last character and I am unable to concatenate the string.
right now I am not creating files, just printing all the names.
So, how I can remove the '\n' from the file name, and is my understanding correct ?

Answer 1

Analysis
There are multiple issues to address in your script. Let's take it step by step:
tempDir=./tmp/
logDir=./logs/
for file in $( find `echo $logDir` -type f )
This scheme assumes no spaces in the file names (which is not an unusual restriction; avoiding problems with spaces in names is relatively tricky). Also, there's no need for the echo; just write:
for file in $(find "$logDir" -type f)
Continuing:
do
name=eval basename $file
This runs the basename command with the environment variable name set to the value eval and the argument $file. What you need here is:
name=$(basename "$file")
where the double quotes aren't strictly necessary because the name can't contain spaces (but it's not a bad habit to get into to quote all file names because sometimes the names do contain spaces).
echo $name
This would echo a blank line because name was not set.
name=$(echo $name | sed 's/.$//')
If name was set, this would chop off the last character, but if the name was A, you'd have nothing left.
echo $tempDir
opFile=$tempDir$name
echo $opFile
done
Give or take double quotes and the fact that you've not added the _tmp suffix to opFile, there's nothing wrong with the rest.
Synthesis
Putting the changes together, you end up with:
tempDir=./tmp/
logDir=./logs/
for file in $(find "$logDir" -type f)
do
name=$(basename "$file")
echo "$name" # Debug only
echo "$tempDir" # Debug only
opFile="$tempDir${name}_tmp"
echo "$opFile"
done
That shows all the intermediate results. You could perfectly well compress that down to:
tempDir=./tmp/
logDir=./logs/
for file in $(find "$logDir" -type f)
do
opFile="$tempDir"$(basename "$file")"_tmp"
echo "$opFile"
done
Or, using a simpler combination of double quotes because the names contain no spaces:
tempDir=./tmp/
logDir=./logs/
for file in $(find "$logDir" -type f)
do
opFile="$tempDir$(basename $file)_tmp"
echo "$opFile"
done
The echo is there as a surrogate for the copy or move operation you plan to execute, of course.
EDIT: ...and to remove restrictions on file names containing spaces and globbing characters, do it as:
tempDir=./tmp/
logDir=./logs/
find "$logDir" -type f |
while IFS= read -r file
do
opFile="${tempDir}${file##*/}_tmp"
echo "$opFile"
done
It will still fail for file names containing newlines. If you want to handle that then investigate a solution using find ... -print0 | xargs -0 or find ... -exec.

Answer 2

Try the following.
#!/bin/sh
tmpDir=./tmp/
logDir=./logs/
# list all files in log directory, pipe into a loop that reads each path line
# by line..
# Also note that there is no newline in this case since it is swallowed by 'read'.
find $logDir -type f | while read path; do
# get the basename of the path
name=`basename $path`
# copy the found file to the temporary directory.
dest="$tmpDir/${name}_tmp"
echo $dest
done
Shell scripts have the ability to concatenate strings easily in statements, as demonstrated with $tmpDir/${name}_tmp, there is no need for replacing the output since read swallows any newlines.
find ... while read is a very useful construct when you want to read multiple lines of anything, it even works for files.
while read line; do
echo $line
done < filename.txt
Edit: clarified

Answer 3

Try something like this:
tempDir=./tmp/
logDir=./logs/
for file in $( find `echo $logDir` -type f )
do
name=`eval basename $file|tr -d "\n"`_tmp
echo $name
done

Answer 4

If you change
name=eval basename $file
to
name=`eval basename $file`
then afterwads name contains what you want.