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https://github.com/autistic-symposium/shell-whiz-toolkit.git
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97 lines
No EOL
1.9 KiB
Markdown
97 lines
No EOL
1.9 KiB
Markdown
Wild Cards
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----------
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Use *, ? (for one char), and [abc] for a series of options. Example:
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$ ls [abc]*
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More commands on one line
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-------------------------
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Use ;
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$ date;who
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Redirection of Standard output/input
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-----------------------------------
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>, >>, <
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Examples:
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$ sort < filename > sorted_names
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Pipes
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-----
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A pipe is nothing but a temporary storage place where the output of one command is stored and then passed as the input for second command.
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Processes and PID
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-----------------
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An instance of running command is called process and the number printed by shell is called process-id (PID), this PID can be use to refer specific running process.
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ps - show current running
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kill {PID} - kill process
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kill 0 - stop all processes except shell
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& - background process
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ps aux - display the owner of the processes along with the processes
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ps -ag - get information of all running processes
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ps ax | grep processes-you-want-to-see
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top - see currently running processes and other information like memory and CPU
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pstree - display a tree of processes
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Useful Cmds:
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------------
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List size of folders
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$ du -sh *
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Print calendar:
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$ cal
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Writing and creating a file:
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$ cat > NEWFILE
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--- write here ---
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^D
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De-bug Shell Script
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-------------------
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Use -v and -x option:
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$ sh option SCRIPT
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$ bash option SCRIPT
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Local and Global Variables
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-------------------------
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Whenever you type:
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$ /bin/bash
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You start a new shell where the previous variables will be forgotten (local variables). To make variables global, you can do:
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$ export VARIABLE-NAME
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Before changing shell.
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Conditional Execution
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---------------------
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The control operators are && (AND) and || (OR).
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$ rm myf && echo "File is removed successfully" || echo "File is not removed"
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Functions
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---------
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$ SayHello()
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{
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echo "Hello $LOGNAME, Have nice computing"
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return
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}
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To execute this SayHello() function just type it name as follows:
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$ SayHello |