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--- lwc:programming:bash [2022/11/04 14:04] – John Harrison
+++ lwc:programming:bash [2024/09/27 12:48] (current) – [Superuser] John Harrison
@@ Line 121: / Line 121: @@
 convert -threshold 75% input.pdf output.pdf
 </code>
+determine resolution of images inside a pdf: ''pdfimages -list EXAMPLE.pdf''
 ==== INTERNET ====
-**ssh no password:** follow [[http://www.thegeekstuff.com/2008/11/3-steps-to-perform-ssh-login-without-password-using-ssh-keygen-ssh-copy-id/|these]] instructions
+  * **ssh no password:** follow [[http://www.thegeekstuff.com/2008/11/3-steps-to-perform-ssh-login-without-password-using-ssh-keygen-ssh-copy-id/|these]] instructions
+  * **vpn on Linux 64 bit**: follow [[http://kb.mit.edu/confluence/display/istcontrib/Cisco+AnyConnect+Certificate+Error+on+Linux|these]] instructions
-**vpn on Linux 64 bit**: follow [[http://kb.mit.edu/confluence/display/istcontrib/Cisco+AnyConnect+Certificate+Error+on+Linux|these]] instructions
+  * **Remote Desktop (VNC through SSH tunnel)**
+    * ssh -L 5901:localhost:5900 UserName@host.com
-**Remote Desktop (VNC through SSH tunnel)**
+    * (in a separate terminal): xtightvncviewer -encodings tight localhost:1
+  * ssh to a host through another (jump) host
-  * ssh -L 5901:localhost:5900 UserName@host.com
+    * use ''-J'' i.e. ''ssh -J user@jumphost user@host''
-  * (in a separate terminal): xtightvncviewer -encodings tight localhost:1
+    * also works for scp i.e. ''scp -J user@jumphost file user@host''
 **DHCP Server and Firestarter (on 12.04)**
   * sudo apt-get install dhcp3-server
   * sudo ln -s /etc/dhcp/dhcpd.conf /etc/dhcpd.conf
@@ Line 181: / Line 181: @@
 <code>sudo lsof -i:8078</code>
+==== Superuser ====
+=== Execute sudo cmd without needing to type password ===
+== Staying Safe ==
+  - backup ''/etc/sudoers'' file i.e. copy to somewhere safe
+  - leave at least one terminal window open as root
+  - edit ''/etc/sudoers'' with ''visudo'' not ''sudo''. It's a wrapper for your already configured editor (not necessarily vi)
+== The Magic ==
+  * create a wrapper script that does all your magic for you. Don't add sudo to the cmds in the wrapper script
+  * using ''visudo'' add to the end of your ''/etc/sudoers'' file ''USERNAME ALL=(ALL:ALL) NOPASSWD: FULL_PATH_TO_SCRIPT'' substituting in USERNAME and FULL_PATH_TO_SCRIPT as necessary
+  * to execute the cmd without password type ''sudo FULL_PATH_TO_THE_SCRIPT''
 ===== Misc =====
    * write to dmesg: ''echo Some message > /dev/kmsg''
-   * add timestamp to log entries that are piped. Add to pipe: '' awk '{ print strftime(), $0; fflush() }' ''
+   * add timestamp to log entries that are piped. Add to pipe: ''gawk '{ print strftime(), $0; fflush() }' ''
+     * ''awk'' is supposed to do this but at least when then piping to ''grep'' only ''gawk'' worked.
    * remove package with all its dependencies. As root: ''apt-get purge `apt-get -s purge <PKG> | grep '^ ' | tr -d '*'`''
    * [[https://tldp.org/LDP/abs/html/tabexpansion.html|autocomplete parameters in bash script]]
    * traverse through to see what is using disk space: ''du -cha --max-depth=1 /var | grep -E "M|G"''
+   * find out what app is on a particular port: ''netstat -anpe | grep "1234" | grep "LISTEN"''