bash - Focused for Success, Inc.

How Do I Quote Properly in Bash?

Back when terminals were used instead of desktops, the shell (either CMD or /bin/sh) was the way most programmers interacted with a computer. Today, filenames are routinely created with characters the shell considers delimiters.

bash

How Do I Setup a Linux Service with Child Processes?

There are many reasons for running a Linux service. Linux provides multiple mechanisms to so. Before systemd, it was difficult to start a service and keep it running. Like any program, it's possible for the process to die, systemd will restart it. The example

linux

How Do I Perform a Netstat in a Docker Container?

A script to use /proc when netstat is missing.

bash

How Do I Use jq to Find Stuff?

An example of how to use jq.

bash

How Do I Make an AWK Shebang Script?

Use #! in a shell script to select the program to run instead of the shell.

bash

How Do I Get a Nice git log?

This is a nice command to get a list of commits with messages for each in a list: git log --pretty=oneline --abbrev-commit git log --pretty=format:"%cd %h %s"

bash

How Do I Wrap a Word using Vi?

According to http://vimregex.com, the {-} construct will do a non-greedy match. I've been searching for this for a long time. For instance, let's say I have used inline quotes for a Markdown doc and I want to change them to bold using

bash

How Do I Test My Home Network Speed?

SSH to the remote computer. Run: while sleep 2 do nc -l 9999 | dd of=/dev/null 2>&1 | awk '/MB\/s/ {print $10 * 8 "Mbps"}' done Send data to the remote computer using this script: while sleep

bash

How Do I Test For RegExp In Bash?

if [[ "$1" =~ s.* ]] then echo small elif [[ "$1" =~ l.* ]] then echo large else echo small or large fi See: Bash V3.2 Reference Manual

bash

How Do I Monitor Progress or Watch a Command in Linux?

Often times it's necessary to watch progress of things like copying a file or checking if a process is still running. This is a job for the Linux "watch" command.

bash

How Do I Trap Exit in a Shell Script?

Often times it is necessary to do things that need to be cleaned up when a shell script exits, remove temporary files for instance. Cleanup should occur when the script exits normally or when it is interrupted. Interruptions can be a BREAK (usually ^C)

bash

How Do I Delete an SSH Key Quickly?

If you build a lot of systems and use SSH you'll undoubtedly run into this problem a lot: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It

bash

How Do I Use cut When My Output Uses Spaces?

The cut command is very useful for picking things like finding the PID of a process to kill. However, the default delimiter is TAB, making the cut command rather difficult to use. The solution is to squeeze the redundant spaces into a single space

bash

How Do I Setup Git To Handle CRLF Properly?

This sets up your account to save any file converted from CRLF to LF with LF instead of converting them to CRLF. This is necessary for running shell scripts on Cygwin. $ git config --global core.autocrlf input $ git config --global -l core.autocrlf=input

bash

How Do I Find More Recent File Modified In A Directory Tree?

This Stack Overflow article covers the subject well: http://stackoverflow.com/questions/4561895/how-to-recursively-find-the-latest-modified-file-in-a-directory This is a slightly modified example: $ find . -type f -printf "%T@ %p\n" | sort -n | cut -f2- -d" " | tail -7 ./dir_a/README.md ./dir_a/hello.java ./dir_b/

bash

How Do I Login via SSH Without a Password?

I use SSH and SCP commands in the shell and in scripts, a lot. Entering a password every time gets tiresome. Fortunately SSH can authenticate automatically if you store the private key of the remote system on your computer. I've been using this "

bash

How Do I Change Colors of My Linux Shell?

Do you use Vim in a black background Linux shell? Chances are you'll find the default colors for Vim or ls are hard to read, especially blue on black. Tell Vim You are using a Dark Background Configuring Vim is done by adding commands

bash

How Do I View Contents of Tar File?

How do you list the contents of a tar file in a tar file? Until recently, I had to untar the file then use tar tf to list the contents of the embedded tar file. To my surprise I found that Vim can actually

bash

How Do I SSH Into a VM Using NAT?

I use Linux in Virtual Machines all the time. Most of the time I setup the VM with a bridged network adapter and SSH. This allows the VM to access the Internet and allows logging into the shell remotely using SSH. Sometimes it's not

bash

How Do I Run SSHD on Windows?

Cygwin has all of the Linux goodies, making Windows a tolerable development platform. It provides the standard OpenSSH packages. Install Cygwin. Install openssh clients and servers package. Run ssh-host-config. Skip the install as a service thing, instead just enter: $ /usr/sbin/sshd in the

bash

How Do I Forward Many TCP Ports Using SSH?

This is easiest done using /etc/ssh_config or .ssh/config. The format of the file is: Host SSHConfigKeyword parameters... You can list specific host names or use * to apply configuration to all hosts you plan to connect to. The file below will forward

bash

How Do I Change the sudo timeout?

sudo visudo add Defaults timestamp_timeout=-1

bash

How Do I Use Getopt?

Here's a simple example: #!/bin/bash # http://www.tutorialspoint.com/unix_commands/getopt.htm usage() { echo usage: $0 -- --ge0IP 10.132.56.250 --ge1IP 192.168.99.1 exit 1 } # read the options TEMP=`getopt --long ge0IP:,ge1IP: -- "$@"` eval set -- "$TEMP"

bash

How Do I Split A String in BASH?

Here's an example: #!/bin/bash IP=192.168.11.1 function split() { export IPARRAY IFS='.' read -ra IPARRAY Output: process 192 process 168 process 11 process 1 192 168 11 1 192

bash

Why Do I Get a Syntax Error in My CYGWIN Shell Script?

DOS File Format Error If you use Cygwin to write shell scripts on Windows, chances are you'll accidentally create a shell script in DOS format. When this happens Bash will flag a syntax error in the script. Usually it looks like a string has