Linux Tidbits and Collecting Pebbles
6 months ago
- #System Administration
- #Linux
- #UNIX
- The author shares their journey with Linux and open source, influenced by UNIX principles.
- Explains that /dev partition is built on-the-fly during kernel boot and resides in memory as devtmpfs.
- Highlights differences between initrd (compressed filesystem) and initramfs (compressed cpio archive).
- Mentions logical working directory in shells and how 'cd..' manipulates it.
- Notes that shell aliases are processed during input reading, not command execution.
- Clarifies C strings are arrays of char, not unsigned char.
- States that GNU grep uses PCRE, not Perl.
- Explains rsync only checks the last modification timestamp, not metadata changes.
- Describes VFS as an abstraction layer for filesystems in Linux.
- Notes kernel tasks are forked from PID 2 (kthreadd).
- Differentiates 'ls' (file size) from 'du' (actual disk usage).
- Mentions signal numbers in Linux go up to 64.
- Describes assembly as human-readable machine code.
- Explains CPU executes machine code derived from assembly.
- Clarifies bash -c assigns the first argument to $0, not $1.
- Notes differences in cron between UNIX System III and V.
- Differentiates mouse (relative positioning) from touch devices (absolute positioning).
- States POSIX specifies C API, not implementation.
- Mentions file creation time usually can't be changed from userspace.
- Explains Ctrl+C sends SIGINT to foreground processes.
- Notes 'su' blocks SIGINT and SIGQUIT when elevating privileges.