Here-strings in bash are implemented via temporary files, usually in the format /tmp/sh-thd.<random string>, which are later unlinked, thus making them occupy some memory space temporarily but not show up in the list of /tmp directory entries, and effectively exist as anonymous files, which may still be referenced via file descriptor by the ...

In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &amp;; echo $! will return the PID of the process which backgrounded myprog...

(From the Bash man page: "Any part of the pattern may be quoted to force it to be matched as a string."). Here in Bash, the two statements yielding "yes" are pattern matching, other three are string equality:

On our school system, we're able to run script files without typing bash or csh or what have you without indicating what script type it is. On Ubuntu, however, I'm required to type bash script.bash...

Furthermore, you also have || which is the logical or, and also ; which is just a separator which doesn't care what happend to the command before.

Aliases are not present "in the system". They are present in a given shell process. There is no way for a shell process to transmit its aliases to a child process. The login shell source s several files from /etc (the only one I remember is /etc/profile), in addition to .profile and .bashrc. If you source the same files in your script, you'll have those aliases too.

To combine stderr and stdout into the stdout stream, we append this to a command: 2&gt;&amp;1 For example, the following command shows the first few errors from compiling main.cpp: g++ main.cpp 2&...

One way to begin debugging your bash script would be to start a subshell with the -x option: ... This will show you every command, and its arguments, which is executed when starting that shell. The --login option is specified because .bash_profile is read by login shells.

The =~ operator is a regular expression match operator. This operator is inspired by Perl's use of the same operator for regular expression matching. The [ [ ]] is treated specially by bash; consider that an augmented version of [ ] construct: [ ] is actually a shell built-in command, which, can actually be implemented as an external command. Look at your /usr/bin, there is most likely a ...

Take careful note of the spaces and also ` is not ' While Radu's answers, and the comments, are exhaustive and very helpful, they are bash-specific. I know you did specifically ask about bash, but I thought I'd pipe in since I found this question when I was looking to do the same thing using sh in busybox under uCLinux. This portable beyond bash.