Shell
How can I delete duplicate lines in a file in Unix?
seen is an associative-array that Awk will pass every line of the file to. If a line isn’t in the array then seen[$0] will evaluate to false. The ! is a logical NOT operator and will invert the false to true. Awk will print the lines where the expression evaluates to true. The ++ increments seen so that seen[$0] == 1 after the first time a line is found and then seen[$0] == 2, and so on. Awk evaluates everything but 0 and "" (empty string) to true. If a duplicate line is placed in seen then !seen[$0] will evaluate to false and the line will not be written to the output
How to use unicode characters in Windows command line?
In powershell type:
It will change the code page to UTF-8. Also, you need to use Lucida console fonts.
(I use this to build a hakyll project on Windows)
Another answer at Windows 10 terminal encoding.
Append Current Date To Filename in Bash Shell
To get the current date in mm_dd_yyyy format use the following date format syntax:
You can store this to a variable name:
or
Finally, you can create a filename as follows:
You can create a shell script as follows:
#!/bin/bash
_now=$(date +"%m_%d_%Y")
_file="/nas/backup_$_now.sql"
echo "Starting backup to $_file..."
# mysqldump -u admin -p'myPasswordHere' myDbNameHere > "$_file"How to check spelling at the Linux command line with Aspell
To check the spelling of a file, just type:
How do I scroll in tmux?
Ctrl-b then [ then you can use your normal navigation keys to scroll around (eg. Up Arrow or PgDn). Press q to quit scroll mode.
How do you scroll up/down on linux server (terminal)?
SHIFT+Page Up and SHIFT+Page Down. If it doesn’t work try this and then it should:
Go the terminal program, and make sure Edit/Profile Preferences/Scrolling/Scrollback/Unlimited is checked.
chmod Numerical permissions
| # | Permision | rwx | Binary |
|---|---|---|---|
| 7 | read, write, and execute | rwx |
111 |
| 6 | read and write | rw- |
110 |
| 5 | read and execute | r-x |
101 |
| 4 | read only | r-- |
100 |
| 3 | write and execute | -wx |
011 |
| 2 | write only | -w- |
010 |
| 1 | execute only | --x |
001 |
| 0 | none | --- |
000 |
A permission have 3 numbers: owner, group and anyone else. An example, 744 stands for; the owner can read, write and execute, group and anyone else can read only the file.