cat with output redirection. Syntax:
cat file [file] [[file] ...] > joined-file.
Example with just two files (you can have many more):
$ echo "some text in a file" > file1
$ echo "another file with some text" > file2
$ cat file1 file2 > mergedfiles
$ cat mergedfiles
some text in a file
another file with some text
In case you have "many documents", make use of shell globbing (patterns):
cat input-files-dir/* > joined-file
This will join all files in that directory to the current directory (preventing it to match the output file itself). It is totally independent to the use of
cat and output redirection - it's just Bash providing all the files as arguments to
It will just glue (join) files together as you would do with paper and tape. It does not care about the actual file format being capable of handling this. It will work for text files, but not for PDFs, ODTs, etc. Well, it will glue them together, but it's not a valid PDF/ODT anymore.
Order of joining
As phoibos pointed out the shell globbing will result in alphabetical order of file names. This is how Bash and shell globbing works.
input file is output file error
When the pattern of the input files matches the very same file as being output, this will cause an error. It's a safety feature. Example:
cat *.txt > out.txt run the second time will cause this.
What you can do about it:
- Choose a more specific pattern to match the actual input files, not matching the output name. Example: input files pattern
*.txt with output file
output.out will not collide.
- Work in different directories. In the example above I've used a separate
input-files-dir directory to place all files in, and output to the current working directory. This makes it impossible to get this error.