I have multiple files which I want to concat with cat.
Let's say
File1.txt
foo
File2.txt
bar
File3.txt
qux
I want to concat so that the final file looks like:
foo
bar
qux
Instead of this with usual cat File*.txt > finalfile.txt
foo
bar
qux
What's the right way to do it?
In python, this concatenates with blank lines between files (the , suppresses adding an extra trailing blank line):
print '\n'.join(open(f).read() for f in filenames),
Here is the ugly python one-liner that can be called from the shell and prints the output to a file:
python -c "from sys import argv; print '\n'.join(open(f).read() for f in argv[1:])," File*.txt > finalfile.txt
You may do it using xargs if you like, but the main idea is still the same:
find *.txt | xargs -I{} sh -c "cat {}; echo ''" > finalfile.txt
If it were me doing it I'd use sed:
sed -e '$s/$/\n/' -s *.txt > finalfile.txt
In this sed pattern $ has two meanings, firstly it matches the last line number only (as a range of lines to apply a pattern on) and secondly it matches the end of the line in the substitution pattern.
If your version of sed doesn't have -s (process input files separately) you can do it all as a loop though:
for f in *.txt ; do sed -e '$s/$/\n/' $f ; done > finalfile.txt
If you have few enough files that you can list each one, then you can use process substitution in Bash, inserting a newline between each pair of files:
cat File1.txt <(echo) File2.txt <(echo) File3.txt > finalfile.txt
That's how I just did it on OsX 10.10.3
for f in *.txt; do (cat $f; echo '') >> fullData.txt; done
since the simple 'echo' command with no params ended up in no new lines inserted.
This works in Bash:
for f in *.txt; do cat $f; echo; done
In contrast to answers with >> (append), the output of this command can be piped into other programs.
Examples:
for f in File*.txt; do cat $f; echo; done > finalfile.txt(for ... done) > finalfile.txt (parens are optional)for ... done | less (piping into less)for ... done | head -n -1 (this strips off the trailing blank line)Source: Stackoverflow.com