Bash: adding commas in for loop

Shell Programming and Scripting
1

Dear Experts

I think this is possibly the easiest thing. but I am not able to solve:

I need comma to be added to end of each line echo'd. But does not want it to be added to last line.

I have a script which does some data analysis and creates a command as in below code snippet

for file in $(sort -u -k3nr data  | cut  -d, -f2| head -5 | tr -d ' ')
do
 echo "\"<grep -w $file data\"  using 1:3 title '$file' with linespoints ,\\"
done

Now output I get is

"<grep -w dir1 data" using 1:3  title 'dir1' with linespoints ,\
"<grep -w dir23 data" using 1:3  title 'dir23' with linespoints ,\
"<grep -w whatever data" using  1:3 title 'whatever' with linespoints ,\

Now I don't want to have comma and slash on last line.

I don't know how many sort command will pull out. and also don't want to have a command wc -l to calculate before hand. I have been trying echo -e "\b" without
luck ..

any other suggestions

2

Hi,

Try this..!!
This will help you when you write all the commands which you created using a for loop to a file.

Assuming you modify your code as:

 
echo "\"<grep -w $file data\"  using 1:3 title '$file' with linespoints ,\\" >> cmd.txt

Use the below code to remove ,\ from last line

sed  '$s/,\\$//' cmd.txt
3

Thank you :slight_smile: . This is really good.
Usually I dont like to create a temp file. Had a bad experience

I am keeping everything in variable and want to execute the command.

Even though I said I dont want to use wc -l .. For now I am doing

nodir=$(sort -u -k3nr data | cut -d, -f2| head -5 | tr -d ' '|wc -l)

and comparing

[[ $nodir > 0 ]] && echo ",\\"
[[ $nodir == 0 ]] && echo " "

4 
for file in $(sort -u -k3nr data  | cut  -d, -f2| head -5 | tr -d ' ')
do
 echo "\"<grep -w $file data\"  using 1:3 title '$file' with linespoints ,\\"
done | sed '$s/...$//'

result=$(
  for file in $(sort -u -k3nr data  | cut  -d, -f2| head -5 | tr -d ' ')
  do
    echo "\"<grep -w $file data\"  using 1:3 title '$file' with linespoints ,\\"
  done
)

echo "${result%???}"
5

Wow .. I knew I asked at right place ..
Thanks a ton guys ..

I like sed .. using sed method
sed '$s/...$//'
or what asterisk gave

sed '$s/,\\$//'