For example, you have already seen a lot of brackets in the examples we have shown over the past several weeks, but the focus has been elsewhere.įor the next phase of the series, we’ll take a closer look at brackets, curly, curvy, or straight, how to use them, and what they do depending on where you use them. I'm not an expert in these so I might have gotten some things wrong.At this stage of our Bash basics series, it would be hard not to see some crossover between topics.

If you want to avoid loosing what has already been written in your log file you can then use the > command in the same ways explained above, but in this case all the outputs will be appended to existing files.įor their use in C++ with cin, cout and cerr I think hash gave a better answer than I could. When you use redirection in this way, bash will not look if the file exists or not and simply create one regardless if that implies erasing the existing one. To understand this command you need to read it form right to left, first a copy of stderr is made to stdout, then strout is redirected to the log.txt file. If you wish to redirect both stdout and stderr you need to duplicate your stderr output to stdout by using the >& command. In order to redirect strerr to you log.txt file you will have to run: command 2> log.txtĪgain, this only redirects strerr. This is similar as calling: command 1> log.txtĪs this only redirects strout you will still be able to see the error in the terminal. You will redirect the output to the file log.txt Normally you would have you would have all FD's pointing to the terminal, but this can be changed by using redirection.įor example, if you call: command > log.txt

These can also be called by FD 0, FD 1 and FD 2 respectively. In bash you have tree standard FD's that are the standard input (strin), the standard output (strout) and the standard error (strerr). The > and > are redirection operators for FD's (File Descriptors)

Brackets ubuntu