Editing Text Images (section)

===Essential commands===
For a PDF with Unix/Linux Command Reference - download the following [https://files.fosswire.com/2007/08/fwunixref.pdf link]

==== System Info ====

'''date''' – Show the current date and time<br /> '''cal''' – Show this month's calendar<br /> '''uptime''' – Show current uptime<br /> '''w''' – Display who is online<br /> '''whoami''' – Who you are logged in as<br /> '''finger ''user''''' – Display information about '''''user'''''<br /> '''uname -a''' – Show kernel information<br /> '''cat /proc/cpuinfo''' – CPU information<br /> '''cat /proc/meminfo''' – Memory information<br /> '''df''' '''-h''' – Show disk usage<br /> '''du''' – Show directory space usage<br /> '''free''' – Show memory and swap usage

==== Keyboard Shortcuts ====

'''Enter''' – Run the command<br /> '''Up Arrow''' – Show the previous command<br /> '''Ctrl + R''' – Allows you to type a part of the command you're looking for and finds it

'''Ctrl + Z''' – Stops the current command, resume with '''fg''' in the foreground or '''bg''' in the background<br /> '''Ctrl + C''' – Halts the current command, cancel the current operation and/or start with a fresh new line<br /> '''Ctrl + L''' – Clear the screen

'''''command'' | less''' – Allows the scrolling of the bash command window using '''Shift + Up Arrow''' and '''Shift + Down Arrow'''<br /> '''!!''' – Repeats the last command<br /> '''''command ''''' '''!$''' – Repeats the last argument of the previous command<br /> '''Esc + . (a period)''' – Insert the last argument of the previous command on the fly, which enables you to edit it before executing the command

'''Ctrl + A''' – Return to the start of the command you're typing<br /> '''Ctrl + E''' – Go to the end of the command you're typing<br /> '''Ctrl + U''' – Cut everything before the cursor to a special clipboard, erases the whole line<br /> '''Ctrl + K''' – Cut everything after the cursor to a special clipboard<br /> '''Ctrl + Y''' – Paste from the special clipboard that '''Ctrl + U''' and '''Ctrl + K''' save their data to<br /> '''Ctrl + T''' – Swap the two characters before the cursor (you can actually use this to transport a character from the left to the right, try it!)<br /> '''Ctrl + W''' – Delete the word / argument left of the cursor in the current line

'''Ctrl + D''' – Log out of current session, similar to '''exit'''

==== Learn more about Commands/programs ====

'''apropos''' '''''subject''''' – List manual pages for '''''subject'''''<br /> '''man -k ''keyword''''' – Display man pages containing '''''keyword'''''<br /> '''man ''command''''' – Show the manual for '''''command'''''<br /> '''man -t ''man'' | ps2pdf - &gt; ''man.pdf'''''  – Make a pdf of a manual page<br /> '''which''' '''''command''''' – Show full path name of '''''command'''''<br /> '''time ''command''''' – See how long a '''''command''''' takes

'''whereis ''app''''' – Show possible locations of '''''app'''''<br /> '''which ''app''''' – Show which '''''app''''' will be run by default; it shows the full path

==== File Commands ====

'''ls''' – Directory listing<br /> '''ls -l''' – List files in current directory using long format<br /> '''ls -laC''' – List all files in current directory in long format and display in columns<br /> '''ls -F''' – List files in current directory and indicate the file type<br /> '''ls -al''' – Formatted listing with hidden files

'''cd ''dir''''' – Change directory to '''''dir'''''<br /> '''cd''' – Change to home<br /> '''mkdir''' '''''dir''''' – Create a directory '''''dir'''''<br /> '''pwd''' – Show current directory

'''rm ''name''''' – Remove a file or directory called '''''name'''''<br /> '''rm''' '''''-r dir''''' – Delete directory '''''dir'''''<br /> '''rm -f ''file''''' – Force remove '''''file'''''<br /> '''rm -rf ''dir''''' – Force remove an entire directory '''''dir''''' and all it’s included files and subdirectories (use with extreme caution)

'''cp ''file1 file2''''' – Copy '''''file1''''' to '''''file2'''''<br /> '''cp -r ''dir1 dir2''''' – Copy '''''dir1''''' to '''''dir2'''''; create '''''dir2''''' if it doesn't exist<br /> '''cp ''file'' /home/''dirname''''' – Copy the filename called '''''file''''' to the '''/home/dirname''' directory

'''mv ''file'' /home/''dirname''''' – Move the '''''file''''' called filename to the '''''/home/dirname''''' directory<br /> '''mv''' '''''file1 file2''''' – Rename or move '''''file1''''' to '''''file2'''''; if '''''file2''''' is an existing directory, moves '''''file1''''' into directory '''''file2'''''

'''more ''file''''' – Display the file called '''''file''''' one page at a time, proceed to next page using the spacebar<br /> '''head ''file''''' – Output the first 10 lines of '''''file'''''<br /> '''head -20 ''file''''' – Display the first 20 lines of the file called '''''file'''''<br /> '''tail ''file''''' – Output the last 10 lines of '''''file'''''<br /> '''tail -20 ''file''''' – Display the last 20 lines of the file called '''''file'''''<br /> '''tail -f ''file''''' – Output the contents of '''''file''''' as it grows, starting with the last 10 lines


==== SSH ====

'''ssh ''user''@''host''''' – Connect to '''''host''''' as '''''user'''''<br /> '''ssh -p ''port user''@''host''''' – Connect to '''''host''''' on port '''''port''''' as '''''user'''''<br /> '''ssh-copy-id ''user''@''host''''' – Add your key to '''''host''''' for '''''user''''' to enable a keyed or passwordless login


==== meta characters ====
Meta Characters are characters that have special meaning within the terminal

* <code>~</code> the tilde stands for the user's home. <code>cd ~/</code> change directory to home
* <code>.</code> dot stands for '''this''' directory. <code>ls .</code> list this directory
* <code>..</code> dot dot stands for '''the parent directory''' to this directory. <code>cp myfile.jpg ..</code> copy myfile.jpg to the parent directory
* <code>*</code> asterisk is a wildcards which represents zero or more characters <code>ls P*.jpg</code> will list all the files, in the current directory, that begin with P and end with .jpg
* <code>\</code> backslash it is a literal character. It escape the meta value of the meta-characters and display them only as literal characters. <code>echo Foo \*</code> will output <code>Foo *</code> If \ wasn't there it would output all the files in that directory.


==== pipes, write to & append ====
'''A pipes (" | ") sends the output of one program to the input of another program'''.

<code>echo "my sentence"| wc</code> the echoed sentence "my sentence" is ''pipped'' into the program wc which counts the number of lines, words, and characters


<code>></code> Writes the output of a command to a file, rather than to print on terminal.

<code>df > df_output.txt </code> redirect the content of <code> man dfM </code> to a file called df_output.txt

If the said file doesn't exit it will create it, if it already exists it will overwrite its contents/


<code>>></code> appends the output of a command to a file, without overwriting the original file.
<code> echo 'also add this' >> df_output.txt </code> will add 'also add this' to the contents of df_output.txt