Getting the last match in a file using grep
You could try grep pattern file | tail -1 or tac file | grep pattern | head -1 or tac file | grep -m1 pattern
unix
How to read backward from the end of file in less or more?
I’m sure someone else has a better answer, but With “less” after you’ve opened the file: G goes to the bottom of the file ^b goes up one page ? searches backwards. As you said, you can open the file with +G and then use ? and ^b to scroll up. There are likely clever … Read more
How do I do ‘mount –bind’ in /etc/fstab?
The mount command accepts –bind or -o bind. In the /etc/fstab file, you can use the following line: /source /destination none defaults,bind 0 0
What is special about /dev/tty?
The ‘c’ means it’s a character device. tty is a special file representing the ‘controlling terminal’ for the current process. Character Devices Unix supports ‘device files’, which aren’t really files at all, but file-like access points to hardware devices. A ‘character’ device is one which is interfaced byte-by-byte (as opposed to buffered IO). TTY /dev/tty … Read more
binary operator expected error when checking if a file with full pathname exists
Looks like your $pathname includes more than one word. Could be multiple lines in your .rm.cfg file, or perhaps the path includes spaces. Anyway, you end up with which is no good. If you’re just expecting a single path and want to protect against the path containing whitespace, change your if line to
SCP Permission denied (publickey). on EC2 only when using -r flag on directories
The -i flag specifies the private key (.pem file) to use. If you don’t specify that flag (as in your first command) it will use your default ssh key (usually under ~/.ssh/). So in your first command, you are actually asking scp to upload the .pem file itself using your default ssh key. I don’t … Read more
What is the difference between a symbolic link and a hard link?
Underneath the file system, files are represented by inodes. (Or is it multiple inodes? Not sure.) A file in the file system is basically a link to an inode.A hard link, then, just creates another file with a link to the same underlying inode. When you delete a file, it removes one link to the … Read more
Rename multiple files based on pattern in Unix
There are several ways, but using rename will probably be the easiest. Using one version of rename: Using another version of rename (same as Judy2K’s answer): You should check your platform’s man page to see which of the above applies.
How can I send an email through the UNIX mailx command?
an example to send attachment and to send attachment AND write the message body
Reasoning behind C sockets sockaddr and sockaddr_storage
I’m looking at functions such as connect() and bind() in C sockets and notice that they take a pointer to a sockaddr struct. I’ve been reading and to make your application AF-Independent, it is useful to use the sockaddr_storage struct pointer and cast it to a sockaddr pointer because of all the extra space it … Read more