The general format of the || is:
command1 || command2
The operation of the || is slightly different. If the command on the left of the || (command1) fails then execute the command on the right of the || (command2); or to put it another way, ‘If this command fails’ || ‘then execute this command’.
Here’s another simple example that illustrates the use of the ||:
$ cp wopper.txt oops.txt || echo "if you are seeing this cp failed" cp: wopper.txt: No such file or directory if you are seeing this cp failed
The copy has failed so now the command on the right-hand side of the || is executed.
A more practical example is this. I want to extract the first and fifth fields from an accounts file and stick the output into a temp file. If ...