Make things happen quickly without touching the mouse
The lower-left corner is less popular location on Mac than Windows. Mac, Windows, and Linux systems have a hosts file that locally does the work of the public DNS – translating host names (typed on browser address field) to IP address numbers. Show text file contents to the Terminal console: cat /etc/hosts The default contents.
This tutorial describes how to make use of the macOS Terminal to make your life easier and less frustrating.
What Apple calls the Terminal is what Linux people call the shell console (more specifically, the Bash shell). It’s also called a command-line terminal, abbreviated as CLI.
Information here is often used in interview questions.
On the Mac, the Terminal app is kinda buried, probably perhaps because those who use a MacOS laptop just for social media probably won’t need a Terminal.
But if you’re a developer, it’s hard to get away from using a CLI.
There are different ways to open a Terminal command line.
My preferrence is a way that doesn’t require reaching for a mouse and using the least number of keystrokes:
Alternately, if you prefer moving your mouse:
PROTIP: If you are at the Finder program (since Yosemite) you can open a Terminal to a folder listed within Finder by pointing your mouse on it, then tapping with two fingers on the touchpad/mousepad.To enable that:
I put in an echo in the various files that macOS executes upon user login, when a new terminal is opened, and when a bash shell is invoked:
When macOS logs in a user, it executes file /etc/profile. That file’s code:
echo ${BASH-no} resolves to /usr/local/bin/bash.
The /etc/bashrc file contains:
The above defines the $PS1 variable which sets the Terminal’s prompt to the left of the cursor.
NOTE: On Ubuntu, instead of /etc/bashrc, the file is /etc/bash.bashrc.
RedHat also executes /etc/profile.d if the shell invoked is an “Interactive Shell” (aka Login Shell) where a user can interact with the shell, i.e. your Terminal bash prompt.
Thus, whatever is specified in /etc/profile is NOT invoked for “non-interactive” shells invoked when a user cannot manually interact with it, i.e. a Bash script execution.
PROTIP: One can change those files, but since operating system version upgrades can replace them without notice, it’s better to create a file that is not supplied by the vendor, and within each user’s $HOME folder: ~/.bash_profile
In other words, file /etc/profile is the system wide version of ~/.bash_profile for all users.
Examples of custom settings include:
export HISTSIZE=1000 # sets the size of .bash_history lines of command history (500 by default)
Wikipedia says umask controls how file permissions are set for newly created files. Please read it for the whole story on this.
To identify the User Mask for permissions:
Since the default is “0022”:-S shows the symbolic equivalent to “0022” for u=user, g=group, o=others :
r is for readable, x is for eXecutable by the user.
To set the User Mask for permissions:
UMASK 077
Many prefer the terminals built into VS Code and other editors/IDEs.
This page contains notes for system administrators and developers,who need to control Macs below the UI level, which requiretyping commands into a command-line terminal screen.
Get the .dmg installer from the websitehttps://hyper.is. It’s used by tutorials author Wes Bos.
Unlike Apple’s Terminal, which is closed-source, Hyper is an open-source and extensible terminal emulator. It is available on MacOS, Windows, and Linux because it’s built using Electron (the same platform that powers Atom, Slack, and Brave). So it can be slow.
To customize Hyper, add the name of many packages to its config file ~/.hyper.js. Build an extension based on hyper.is/#extensions-api.
Many prefer to install and use iTerm2 instead of the built-in Terminal program.Install iTerm2 using Homebrew:
Terminal does not support but iTerm2 does support dividing the CLI into several rectangular “panes”, each of which is a different terminal session:
Pressing the shortcut again restores the hidden panes.
On Linux, there is the screen command.
See Iterm2 Cheat Sheet of iTerm2 keyboard shortcuts. https://github.com/nobitagit/iterm-cheat-sheet/blob/master/README.md
A list of all commands native to macOS is listed alphabetically at https://ss64.com/osx.
To exit from the Terminal shell:
exit
Get back in for the remainder of this tutorial.
CAUTION: To kill all apps and shutdown a Mac right away (with no warning and no dialog):
sudo shutdown -h now
These come from the bash terminal on Linux machines here: Press control with your pinkie, then …
A big reason to use a command-line terminal is to set environment variables.
Like on PCs, the PATH system environment variable storeswhere the operating system should look to find a particular program to execute.
To see what is already defined:
The listing such as this, which declares the “XPC_FLAGS” system variable: /mac-miller-self-care-mp4-video-download.html.
declare -x XPC_FLAGS=”0x0”
This talks about setting launchd.conf and rebooting.This applies to all users.
To see what is defined:
PROTIP: $PATH must be upper case.
The response I’m getting includes:
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
Notice colon (:) separator used in Mac and Linux vs. semicolons used in Windows PATH.
The command to invoke the default editor is defined by a variable:
By default, it’s TextMate:
If you want to change it to nano or other editor, see My tutorial on text editors.
On Terminal session, copy what has been typed and open the default text editor so you can edit the command:
Alternately, (which also works in Linux) while holding down the control key, press X and E together:
control + X + E
Make changes, then copy all, switch or exit to the Terminal, then paste.
To switch among programs already running in macOS, hold down the command key while pressing tab multiple times until the program you want is highlighted (with its name) in the pop-up list. This is equivalent to the Windows control+Esc key combo.
List previous command history:
This is the same as:
PROTIP: History does not display commands entered with a leading space.
Cursor up and press Enter to re-execute.
Press control + R to begins a “reverse incremental search” through your command history,then type, it retrieves the most recent command that contains all the text you enter. Much better than something like:
Press control + S to reverse the mode.
Clear history:
The clear command does not clear history.
See history at sstr.com
Clear the terminal history:
clear
List the first process (with Parent process ID of 0) launched (into user space) at boot by the system kernel:
f adds columns for status of the command (CMD) to invoke the process:
By contrast, on Linux system, the first CMD is /lib/systemd/systemd.
To list all processes, don’t specify 1
To list the process ID given a process name such as “firefox”:
This can be generalized in a shell program containing:
Alternately, Linux has a command which returns the PID associated with a process name. But it’s not avaiable on macOS, so:
install it using Homebrew:
To emulate a long-running process in the foreground:
No additional commands can be accepted.
To kill the current process, press control + C.
Run a program in the background with the &:
List jobs (processes) running in the background:
Do it again:
To suspend the process, press control + Z. The response is like:
[1] shows the PID.
Internally, this sends a “20) SIGTSTP” signal to the process.
To have the process continue (internally sending a “18) SIGCONT”:
List processes
Copy the PID (Process Identifier) number for use in the kill command, such as:
There are many ways to kill a process:
To kill a specific process, ee need to specify its PID (Process Identifier):
Some applications are written to receive a sigterm so that it can take steps to gracefully cleanup and exit.
The key ones, in order of aggressiveness:
kill 289 # sends sigterm
kill -15 289 # sends sigterm
kill -2 289 # sends sigint
kill -1 289 # sends sighup
kill -9 289 # sends sigkill signal to the kernel without notifying the app, a “dirty shutdown” used when the app is misbehaving.
To list process id’s and port (such as 8080), use the “list open files” command:
PROTIP: Use grep to filter because the response is usually too many lines.
(You’ll need to provide your password).
The right-most column heading 'NAME' shows the port(either TCP or UDP).
In Finder, select from the left panel the first item under the Devices list.
Click on Macintosh HD.
Click on your username (wilsonmar in my case).
This action is the same as clicking on the last default item under theFavorites list.
Many WordPress developers prefer to add a folder named Siteswhich holds the wordpress folder expanded from download.
VIDEO:On both Mac and Linux, the “et-see” folder contains system and program configuration files,for both default system and programs you install (such as “teamviewer”, etc.)
/bin contains system
/sbin are for system administrators such as ping, fdisk, mount, umount, etc.
By default, the Terminal shows the hard drive and lowest level file folder name, in white letters over black.
To show the present (current) working directory (folder):
The response for me is:
/Users/wilsonmar
You will of course have a different machine user name than wilsonmar.
Note the pwd command is built internally to the Bash shell:
The response:
pwd is a shell builtin
To get back to the home folder:
Alternately:
Alternately, use the $OLDPWD environment variable that MacOS automatically maintains toremember the previous working directory so that you can switch back to it:
List all file names (without any metadata):
Folders available by default include Documents, Downloads, Pictures, Desktop, Music, Movies.
Note the ls command is an external command added to the Bash shell:
The response lists where ls is defined:
ls is hashed (/bin/ls)
Dive into a folder type:
Press Enter.
Nothing happens because upper case letters are important.
Press delete to remove the mu and type:
Press Enter for the Music folder.
Go back up a level:
Create a Projects folder to hold projects downloaded from Github:
-p specifies creating the parent folder if it doesn’t exist.
This only needs to be done once.
List all files with their permission settings:
Notice that no hidden files are listed.
List all hidden files with permission settings,piping the listing to more instead of having results flying by:
A colon appears at the bottom if there is more to show.
Cancel the listing, press control + C.
Notice the .bashrc on the first page, something like:
(It’s for the Bash Shell.)
If a file is not listed, create it with:
To make it rw r r:
List only hidden files in the current folder:
By default, the Mac’s Finder does not show hidden files.
Close all Finder folders.
Enter this in Terminal before typing Return:
This causes all Finder windows to be reset.
To make invisible files visible again:
A description of each keyword:
defaults - OSX’s command to change defaults, apple’s low-level preference system.
write - tells defaults you want to change a preference, or write it
com.apple.finder - defaults that the application’s preferences you want to change is Finder, specified by the application’s bundle identifier.
AppleShowAllFiles - specifies which preference you want to change within the application.
TRUE or FALSE - the value you want to set the preference to. In this case, it is a boolean, so the values must be TRUE or FALSE. I think you might be able to use YES or NO, but I’m not sure.
&& - a terminal operator to run whatever’s after this if the command to its left is successful.
killall - kills processes or closes applications.
Finder - specifies the process or application to close.
For more on this, see this.
Most developers leave files un-hidden.
To set wireless (device en0) up or down without clicking on the icon at the top:
ifconfig en0 down
This command requires sudo permissions.
Set alias command to just type showFiles andhideFiles to show and hide Mac OS X’s hidden files, considerthis article to create such terminal aliasesin the ~/.bash_profile script.
OSX does not come with the tree command that many other Linux distributions provide. So add it using:
If you don’t want to install a program, add an alias for a tree command by adding this in the ~/.bash_profile script:
Alternately, add it by installing a command using brew:
Active Terminal sessions need to be closed so new Terminal Shell New Window Shell has this activated.
See list of parameters:
List only 2 levels deep with human-readable file size kilobytes and sort by last modified date:
By default, if you move the mouse to one of the corners of the screen,stuff happens. It can be annoying.
Select actions for each of the corners.
PROTIP: Disable each by selecting the dash (last choice) so they don’t show up when you’re just trying to navigate to something near the edge.
Press Esc to bring the screen back.
PROTIP: NOT having a quick way to “Put display to sleep” is considered a security vulnerability by CIS. The lower-left corner is less popular location on Mac than Windows.
Mac, Windows, and Linux systems have a hosts file that locally does the work of the public DNS– translating host names (typed on browser address field) to IP address numbers.
Show text file contents to the Terminal console:
The default contents:
PROTIP: fe80:: is a block of IPV6 addresses reserved for link-local addresses used for packets sent only to directly connected devices (not routed). The network discovery protocol (NDP), which replaces ARP and DHCP in IPv4, is the biggest user of link-local addresses (NDP sorta .
fe80::1 is like 127.0.0.1 for IPV4, butactually IP address 169.254.. in IPV4, an address not often used.
Each IPV6 interface has a different link-local address starting with fe80:: and (typically) ending with a modified version the interface’s MAC address (EUI-64 format) to ensure a unique address on a segment.
Programs such as OpenVPN add to the bottom of the file:
BLAH: The Linux tac command to list backward is not in Mac:
Show a file in -reverse (bottom-up):
Change n2 to a different number of lines to show.
PROTIP: This command is useful to see the lastest entries appended to the end of a large log file.
Expose spaces at end of lines by showing at end of every line $ end-of-line characters that are otherwise not shown. For example, in a file on every macOS:
Edit the hosts file on a Mac using the Atom text editor:
Find the IP address of a website host name:
To access a remote server through a port that is not open to the public:
VIDEO: Bind local port 3337 to remote host 127.0.0.1 port 6379 using user root in emkc.org
BTW 6379 is the default port for a Redis instance.
Analysis at one time showed this ranking by speed:
Google Namebench tries the speed of various DNS servers from YOUR machine (which takes some time) and pops up in your browser this:
An example:
Flush the DNS cache (since OSX 10.9):
sudo dscacheutil -flushcache
dscacheutil is the Directory Service cache utility used to Gather information, statistics, initiate queries, flush the cache:
BTW, the equivalent for Ubuntu issudo service network-manager restartwhile other Linux flavors usessudo /etc/init.d/nscd restart.
Windows usesipconfig /flushdns.
Different commands are needed for different versions of OS.OSX 10.10 added requirement for sudo when using the built-in discoveryutil:
sudo discoveryutil udnsflushcaches
The profile file is run during boot-upto configure the terminal to define file path, shims, and autocompletion handlers.
This is the single biggest frustration with people using Linux on Mac.
One of the earliest articles on bash hereshows shell variables, environment variables, and aliases.
Each operating system has its own file name for its profile:
PROTIP: If there is both a .bash_profile and a .profile file, boot-up only executes the first one it finds.
On my Yosemite Mac, open a terminal and:
View the file using the vi editor that comes with OSX:
According to the bash man page, .bash_profile is executed during login before the command prompt,while .bashrc is executed for interactive non-login shells such aswhen you start a new bash instance by typing /bin/bash in a terminal.
Here’s what my profile file begins:
Exit vi by typing :q
Some installers request that adding a $PATH using a command such as:
To execute profile with the changes:
Alternately, to install GHC copy and paste into ~/.bash_profile:
https://github.com/gcuisinier/jenv/blob/master/README.md
To run a Bash script while avoiding the confirmation prompt:
set -- -f; source bootstrap.sh
I can use Linux commands in my version of the operating system:
uname -a (a for all) or uname -rvm
returns:
14.3.0 Darwin Kernel Version 14.3.0: Mon Mar 23 11:59:05 PDT 2015; root:xnu-2782.20.48~5/RELEASE_X86_64 x86_64
which is a combination of:
uname -r for release number,
uname -v for kernel version,
uname -m for model:
x86_64 for Intel or AMD 64-bit or
i*86 for 32-bit.
For more information about Darwin operating systemdeveloped at Apple, see:
NOTE: lsb_release -awhich works on Debian, RHEL 6.6, and Ubuntu is not recognized on Gentoo nor CentOS 6,which has no folder /etc/lsb-release.
See Distriwatch.com,which describes releases of different Linux distributions.
Paul Irish is one of top pros among developers, and now a Google Evangelist.He put his Mac configuration settings ongithub.com/paulirish/dotfiles. But he recommends cloning github.com/mathiasbynens/dotfiles/.
On the Git page notice that he has established an industry convention of usingProjects folder we defined earlier.
On the Git page I clicked on Clone in Desktop.
The library is called dotfiles because that’s what hidden files are called,and most configuration files are hidden.
By default, if you have a long file name, it would leave little room to type in commands before it wraps to the next line.
To redefine what appears in the prompt,edit this file using the vi editor that comes with each Mac:vi .bashrc Copy this and paste to the bottom of the .bashrc file:
The command above uses global parameters $USER and $PWD,plus colors from this list.
If you try a command that responds about “permissions denied”, you need to execute as a root user.
The root user has the ability to relocate or remove required system files and to introduce new files in locations that are protected from other users. A root user has the ability to access other users’ files.
Any user with an administrator account can become the root user or reset the root password.
Under a *nix system like MacOS you must have “root” (administrative) privileges to start IP-services using ports smaller than 1024.
After MacOS install, the root or superuser account is not enabled. While it is possible to enable the root account, once enabled, if forgetten, you’ll have to reboot from the installer drive (a hassle).
The easiest way it to have the last command (in history) automatically retrieved so you don’t have to retype it to
execute again under root:
sudo !!
It is safer and easier to use the sudo command to gain temporary root access to the system rather than logging out and logging in using root credentials.
Alternately, this command only reads the $SHELL variable and executes the content:
sudo -s
You would be prompted for a password.
whoami
The response “root” says you’re still in sudo rather than your user name.
exit
PROTIP: There are several ways to invoke sudo*
This command is my preferred way to get into root for awhile because it keeps the environment variables intact:
sudo /bin/bash
The command above uses a non-login shell, and reads just the .bashrc of the calling user. Not all dot-files are executed.
If you want environment variables specific to root and be in the root home directory (rather than your user’s $HOME directory), this command executes /etc/profile, .profile, and .bashrc which defines them:
sudo su -s
If you switch between Zsh and Bash, this command runs the shell specified by the password database entry of the target user as a login shell:
sudo -i
If you switch between Zsh and Bash, this command runs the shell specified by the password database entry of the target user as the login shell, then executes login-specific resource files .profile, .bashrc (or .login):
sudo -s
NOTE: The folders that bash looks into are in bin:
/bin/echo $PATH
On a fresh Yosemite, that would contain:
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
Each additional app adds to the front of the list:
/Library/Frameworks/Python.framework/Versions/3.4/bin:/opt/local/bin:/opt/local/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
Separating the folders between colon separator:
New folders are added to the front of the PATH using a command such as:
export PATH=<new folders>:$PATH
Depending on how you’re setup, file ~/.profile or ~/.bash_profile or ~/.bash_login contains the path echo’d.
Or your PATH may be set in /etc/profile for all users
http://www.jesseweb.com/coding/automator/create-windows-like-shortcuts-with-parameters/
Mac OSX doesn’t allow you to create shortcuts like Windows.OSX alias don’t allow parameters (ex. create a Screen Sharing shortcut that connects to a specific computer).
Jessie suggests this to create a Windows like shortcut with parameters in the Comments field.
Another alternativeis to use a text editor to create URL shortcut fileslike the ones Windows Internet Explorer stores its bookmarks. Apple Safari recognizes them when clicked within Finder.So they are cross-platform.
Mount a .dmg (Disk Image) file (substituting for /path/to/diskimage):
The response is like:
Note the disk from the message above to unmount (detatch):
The same utility can mount .iso images:
curl http://localhost:3000
Previously, when invoked on Mac OS 10.10 (Yosemite), you needed to add a parameter to make the request use IPv4:
curl http://localhost:3000 –ipv4
Otherwise, even if the URL loads fine in a browser, you will see an error message such as:
curl: (7) Failed to connect to localhost port 3000: Connection refused
This occurs because curl, under Yosemite, uses IPv6 by default but some apps, such as LoopBack.io, by default uses IP v4.
See if you see IP v6 entries in your hosts file (::1 localhost, fe80::1%lo0 localhost). If they are there it is likely that curl is making requests using IP v6.
You can make your LoopBack app use IPv6 by specifying an IPv6 address as shown below:
Linux has a ncdu (NCurses Disk Usage) utility to list files in order of how much space they occupied.
It’s not in macOS by default, so:
See https://mac.softpedia.com/get/Utilities/ncdu.shtml
Now list files within a folder by space used:
The command takes up the whole screen (like top), so press control+C to exit.
To get the directory utilitization size of the current directory:
The response is like:
The dot means the current folder.
You can specify a sub-folder named, for example, “code”:
When files or folders are moved to Trash, they are sent to folder ~/.Trash.
~ means it is at your user HOME folder.. means it is a hidden folder.List the files.
Count the number files in the folder by piping to the “word count” utility:
(The -al includes hidden files and folders)
(The find . includes files nested within folders as well)
The above command is aliased as cf in my ~/.bash_profile.
To recover disk space taken up by files which have been moved to Trash, there are several ways:
Switch to the Finder and click the Finder menu to expose the menu:
You can click on “Empty Trash” or press the Keyboard sequence shift + command + delete.
If you rather not use a mouse within Finder, switch to Terminal and type this AppleScript command (which will take a while to run if there are a lot of files):
NOTE: How to put the above command is aliased as empty in my ~/.bash_profile.
Schedule Timed Jobs on macOS with launchd within a plist (XML) file.
By default, operating systems limit how many file descriptors to allow.Each operating system version has a different approach.
Linux operating systems have this command:
ulimit -a
On my Sierra the response was:
Check how many file descriptors you have:
launchctl limit maxfiles
On Sierra the response was:
The first number is the “soft” number, the second one is the “hard” number.
After fixing, the numbers I now see are:
Such numbers were set with a command such as:
sudo launchctl limit maxfiles 10240 10240
The maximum setting is 12288?
NOTE: To change maxfiles on Sierra, define a plist. TODO: verify
Due to security, OSX Lion removed the “unlimited” option and now requires a number to be specified.
PROTIP: launchctl is a rough equivalent to the systemctl command used in Linux systems.launchctl interfaces with launchd to load, unload daemons/agents and generally control launchd.
Some programs make calls to the operating system which OSX began to see as a threat, beginning with El Capitan.
Apple says System Integrity Protection blocks code injection (and many other things).
But what about useful programs (such as XtraFinder)which works by injecting its code into Finder and other application processes?
To get around this, you need to partially disable System Integrity Protection in OS X El Capitan.See Apple’s article on how:
Reboot the Mac.
This is needed because System Integrity Protection settings are stored in NVRAM on each individual Mac.So it can only be modified from the recovery environment running in NVRAM.
When the OS X Utilities screen appears, pull down the Utilities menu at the top of the screen.
Type the following command into the terminal before hitting the return key.
For XtraFinder:
To revert SIP to original state:
Video course Mac OS X Support: Installation and Configureis the first of courses on Plurasight towardApple Certified Support Professional (ACSP)
[2] VIDEO
[3] Advanced Bash-Scripting Guide by Mendel Cooper 2012
[4] CommandLineFu.com
https://zwischenzugs.com/2018/01/06/ten-things-i-wish-id-known-about-bash/https://leanpub.com/learnbashthehardway
https://blog.flowblok.id.au/2013-02/shell-startup-scripts.htmlhttps://bitbucket.org/flowblok/shell-startup/src/default/
https://linuxaria.com/howto/7-hidden-features-of-bash
This is one of a series on Mac OSX: