whether or not you can or cannot create a pipe), but named pipes ( made with mkfifo ) do involve typical file permissions and read-write-execute bits. Redirections involve file and directory permissions anonymous pipes typically do not involve permissions (i.e.Pipes | only use pipe() and dup2() syscall.

When redirection is done on files, things like echo 'TEST' > file and echo 'TEST' > file both use open() syscall on that file ( see also) and get file descriptor from it to pass it to dup2().

| pipes are applied only for current command (which means either simple command or subshell like seq 5 | (head -n1 head -n2) or compound commands (but also please note that for such compound commands the amount of bytes that read() consumes will influence how much data is left on the sending end of the pipe for other commands inside the read end of the pipe ).

pipes are not lseek()'able so commands can't read some data and then rewind back, but when you redirect with > or output.txt every command will write to output.txt from then on.

| pipes are not associated with an entry on disk, therefore do not have an inode number of disk filesystem (but do have inode in pipefs virtual filesystem in kernel-space), but redirections often involve files, which do have disk entries and therefore have corresponding inode.

Also please don't be intimidated by the notion of internals or syscalls - you don't have to know or be able to use them in order to understand how shell does things, but they definitely help understanding. I also suggest you try to see how syscalls work in shell with strace command. Don't hesitate to ask questions or suggest improvements in the comments. Note:The answer reflects my own understanding of these mechanisms up to date, accumulated over research and reading of the answers by the peers on this site and, and will be updated as time goes on. If > meant both, it would simply create a new file for you (then warn it doesn't know what to do with log.txt). Right now, if you type ls | gerp log.txt it will tell you bash: gerp: command not found. Thirdly: if you mis-type a command, it wouldn't warn you that the command doesn't exist. If you intended to make a file with that name in your current folder, you'd be stuck. Second example: As Florian Diesch pointed out, what if there's another command elsewhere in the system with the same name (that is in the execute path). You'd have to do something like write the output to a new filename, then rename the file. Presumably, it would try to execute this file, passing the input. There already exists a file with that name that you wish to overwrite. Thing1 > temp_file & thing2 temp_file & thing2 tried to be both 'pass to program' and 'write to file', it could cause problems in both directions.ДЇirst example: You are trying to write to a file. If you want to pass the output from program thing1 to a program called thing2, you could do the following: (Note - if thing2 exists, it will be overwritten)

Everything that thing1 outputs will be placed in a file called thing2.Your shell will run the program named thing1.

Redirect is used to pass output to either a file or stream.Д®xample: thing1 > thing2 vs thing1 | thing2 Pipe is used to pass output to another program or utility.

Indirection redirection memory