Replace whitespace with a comma in a text file in Linux

Question

tr ' ' ',' <input >output 

Substitutes each space with a comma, if you need you can make a pass with the -s flag (squeeze repeats), that replaces each input sequence of a repeated character that is listed in SET1 (the blank space) with a single occurrence of that character.

Use of squeeze repeats used to after substitute tabs:

tr -s '\t' <input | tr '\t' ',' >output 

Try something like:

sed 's/[:space:]+/,/g' orig.txt > modified.txt

The character class [:space:] will match all whitespace (spaces, tabs, etc.). If you just want to replace a single character, eg. just space, use that only.

EDIT: Actually [:space:] includes carriage return, so this may not do what you want. The following will replace tabs and spaces.

sed 's/[:blank:]+/,/g' orig.txt > modified.txt

as will

sed 's/[\t ]+/,/g' orig.txt > modified.txt

In all of this, you need to be careful that the items in your file that are separated by whitespace don't contain their own whitespace that you want to keep, eg. two words.

without looking at your input file, only a guess

awk '{$1=$1}1' OFS=","

redirect to another file and rename as needed

What about something like this :

cat texte.txt | sed -e 's/\s/,/g' > texte-new.txt

(Yes, with some useless catting and piping ; could also use < to read from the file directly, I suppose -- used cat first to output the content of the file, and only after, I added sed to my command-line)

EDIT : as @ghostdog74 pointed out in a comment, there's definitly no need for thet cat/pipe ; you can give the name of the file to sed :

sed -e 's/\s/,/g' texte.txt > texte-new.txt

If "texte.txt" is this way :

$ cat texte.txt
this is a text
in which I want to replace
spaces by commas

You'll get a "texte-new.txt" that'll look like this :

$ cat texte-new.txt
this,is,a,text
in,which,I,want,to,replace
spaces,by,commas

I wouldn't go just replacing the old file by the new one (could be done with sed -i, if I remember correctly ; and as @ghostdog74 said, this one would accept creating the backup on the fly) : keeping might be wise, as a security measure (even if it means having to rename it to something like "texte-backup.txt")

This command should work:

sed "s/\s/,/g" < infile.txt > outfile.txt

Note that you have to redirect the output to a new file. The input file is not changed in place.