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--- mywiki:linux:linuxadmin [2015/02/02 09:20] – shaoguoh
+++ mywiki:linux:linuxadmin [2019/09/15 18:55] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 Linux Admin
-| Reference | [[http://www.er.uqam.ca/nobel/r10735/unixcomm.html|Useful Linux Commands]] |
+| Reference | [[http://www.er.uqam.ca/nobel/r10735/unixcomm.html|Useful Linux Commands]] | [[SSH]] |
-====== Add User to groups ======
+====== Schedule routine with crone ======
+Linux cron utility is an effective way to schedule a routine background job at a specific time and/or day on an on-going basis.
+| Display all scheduled routine  | crontab -l |
+| Add a scheduled routine | crontab -e |
+Routine Format Example:
+4 * * * /opt/comlab/users/shaoguoh/bin/update_outpost_repo.sh https://mts.lantiq.com/~wlnsw/repo/project/ugw /tmp2/shaoguoh/project/ugw.clone_only
+By the way, first 5 digits means: MIN HOUR DOM MON DOW CMD
+– 0th Minute
+– 04 AM
+    * – every day
+    * – every month
+    * – Every day of the week
+====== User groups management ======
+| Set user to a primary group list only | usermod -G groups username  |
+| Add user to other groups based on current groups | usermod -aG additional_groups username |
+| Display user's groups | groups username |
+====== how to know current shell ======
+  * echo $0 - will print the program name... which in the case of shell is the actual shell
+  * ps -ef | grep $$ | grep -v grep - will look for current process ID in the list of running processes. Current process being shell, it will include shell. This is not 100% reliable
+  * echo $SHELL The path to the current shell is in SHELL variable for any shell. it seems not reliable ??
-For example, add user jerry to groups ftp, www_data:
-useradd -G ftp,www_data jerry
 ====== Shorthand at the Command Prompt ======