Concatenating multiple text files into a single file in Bash

What is the quickest and most pragmatic way to combine all *.txt file in a directory into one large text file?

Currently I'm using windows with cygwin so I have access to BASH.

Windows shell command would be nice too but I doubt there is one.

This appends the output to all.txt

cat *.txt >> all.txt

This overwrites all.txt

cat *.txt > all.txt

Just remember, for all the solutions given so far, the shell decides the order in which the files are concatenated. For Bash, IIRC, that's alphabetical order. If the order is important, you should either name the files appropriately (01file.txt, 02file.txt, etc...) or specify each file in the order you want it concatenated.

$ cat file1 file2 file3 file4 file5 file6 > out.txt

The Windows shell command type can do this:

type *.txt > outputfile.txt

Type type command also writes file names to stderr, which are not captured by the > redirect operator (but will show up on the console).

You can use Windows shell copy to concatenate files.

C:\> copy *.txt outputfile

From the help:

To append files, specify a single file for destination, but multiple files for source (using wildcards or file1+file2+file3 format).

Be careful, because none of these methods work with a large number of files. Personally, I used this line:

for i in $(ls | grep ".txt");do cat $i >> output.txt;done

EDIT: As someone said in the comments, you can replace $(ls | grep ".txt") with $(ls *.txt)

EDIT: thanks to @gnourf_gnourf expertise, the use of glob is the correct way to iterate over files in a directory. Consequently, blasphemous expressions like $(ls | grep ".txt") must be replaced by *.txt (see the article here).

Good Solution

for i in *.txt;do cat $i >> output.txt;done