I have a text file that has a space before the line. How do I delete it using tr (or the correct command)?
For example, I have this:
Text
I would like this:
Text
But, how do I do that for a 200 line text file?
I currently have this pipeline:
cat file.txt | tr -s " " | tr -d ","
The other tr commands are for removing other aspects of the text files.
This should do the job:
sed -e 's/^ //' -e 's/,//g' file.txt
The sed command (stream editor) is passed two commands to execute sequentially, both commands substitute something by nothing, i.e. delete a part of the input.
The first one removes spaces immediately following the beginning of a line, noted ^, the second one is removing the commas, and has the very same effect as your tr -d "," command.
Thanks to minerz029 for indirectly reminding me I was missing the 'g' as my first reply was only removing the first comma found in each line.
-e s/^ *// ;-)
sed -e 's/^ //g' -e 's/,//g' file.txt
Explanation:
The first script (s/^ //g) is to replace all leading space with nothing (delete).
The second script (s/,//g) is to replace all commas with nothing (delete).
Bash has a way of using while IFS= read -r ; do . . . done < input.txt structure , to print exact contents of the file, but one of the peculiar features here is that if you omit IFS= , the leading spaces won't be read. Thus, we can do the following:
$ cat input.txt
Text
$ while read -r line; do printf "%s\n" "$line"; done < input.txt
Text
And to replace the text of the original file, one can modify the command slightly like so:
$ cat input.txt
Text
$ while read -r line; do printf "%s\n" "$line"; done < input.txt > temp.txt ; mv temp.txt input.txt
$ cat input.txt
Text
We can also use parameter expansion to delete commas as well
$ cat input.txt
Text, text,
$ while read -r line; do printf "%s\n" "${line//,}"; done < input.txt
Text text
tr -s" " could also be simulated via modifying printf slightly
$ cat input.txt
Text, text,
$ while read -r line; do printf "%s " ${line//,};printf "\n"; done < input.txt
Text text
