Add List The PID And Name Of Current Shell Process as a Unix TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1598 TILs and counting..._
+_1599 TILs and counting..._
 
 See some of the other learning resources I work on:
 - [Ruby Operator Lookup](https://www.visualmode.dev/ruby-operators)
@@ -1575,6 +1575,7 @@ See some of the other learning resources I work on:
 - [List Parent pid With ps](unix/list-parent-pid-with-ps.md)
 - [List Stats For A File](unix/list-stats-for-a-file.md)
 - [List The Available JDKs](unix/list-the-available-jdks.md)
+- [List The PID And Name Of Current Shell Process](unix/list-the-pid-and-name-of-current-shell-process.md)
 - [List The Stack Of Remembered Directories](unix/list-the-stack-of-remembered-directories.md)
 - [List TXT DNS Records For A Domain](unix/list-txt-dns-records-for-a-domain.md)
 - [Load Env Vars In Bash Script](unix/load-env-vars-in-bash-script.md)

unix/list-the-pid-and-name-of-current-shell-process.md

@@ -0,0 +1,27 @@
+# List PID And Name Of Current Shell Process
+
+In Julia Evans' [How to add a directory to your
+PATH](https://jvns.ca/blog/2025/02/13/how-to-add-a-directory-to-your-path/),
+she shows off an odd-looking command for determining what shell (e.g. bash or
+zsh) you are currently running.
+
+```bash
+$ ps -p $$ -o pid=,comm=
+
+38105 -zsh
+```
+
+I already know I'm running `zsh`, but I thought this command was interesting
+enough to dig into and break down.
+
+- The `ps` command lists processes that "have controlling terminals"
+- The `$$` is a special shell variable representing the PID of the current process (try `echo $$`)
+- The `-p` flag allows you to specify a PID for `ps` to grab, in this case, the `$$` PID
+- The `-o` flag allows us to specify the output format, such as the PID and command name
+- The `=` after `pid` and `comm` tell `ps` to exclude headers from the output
+
+Additionally, I noticed that it output `-zsh` (not just `zsh`). That leading
+hyphen seems to indicate that [this `zsh` process is a _login
+shell_](https://unix.stackexchange.com/a/46856/5916). That means it was the
+process used to initiate an interactive shell session and something like the
+`.zprofile` would have been sourced as part of that.