2019-04-23 update

content/blog/print-config-file-without-comments.md

@@ -0,0 +1,47 @@
+---
+title: "Bash Snippet: Print a config file without comments"
+date: 2019-04-23T00:00:00+02:00
+---
+
+Logging in on a server, printing a configuration file and trying to find the relevant setting from thousands of comment lines.
+Sounds familiar?
+
+Not that comments are useless in a configuration file but sometimes it's handy to print a configuration file without the comment lines.
+Especially when the file is thousand lines long but the useful lines fit the twenty five lines of a standard terminal.
+
+The `egrep` command which is standard on most Linux distributions and on MacOS, can strip out the unwanted lines:
+
+```sh
+egrep -v '^\s*(#|$)' /etc/ssh/sshd_config
+```
+
+The `-v` switch prints out the lines that **do not** match the given regex `^\s*(#|$)`.
+And this regex captures:
+
+- empty lines
+- lines with only whitespaces
+- lines that contains only comments
+
+And now, your active sshd configuration fits a 25 lines terminal!
+
+```raw
+$ egrep -v '^\s*(#|$)'  /etc/ssh/sshd_config
+HostKey /etc/ssh/ssh_host_rsa_key
+HostKey /etc/ssh/ssh_host_ecdsa_key
+HostKey /etc/ssh/ssh_host_ed25519_key
+SyslogFacility AUTHPRIV
+PermitRootLogin no
+AuthorizedKeysFile	.ssh/authorized_keys
+PasswordAuthentication no
+ChallengeResponseAuthentication no
+GSSAPIAuthentication yes
+GSSAPICleanupCredentials no
+UsePAM yes
+X11Forwarding yes
+UseDNS no
+AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
+AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
+AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
+AcceptEnv XMODIFIERS
+Subsystem	sftp	/usr/libexec/openssh/sftp-server
+```