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Moving to using dash ‘-‘ as a delimiter

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Spaces or tabs. Using 2 spaces verses 4 spaces. Defining variables as lowercase v InitCap, environment variables UPPERCASE or not, using underscore ‘_’ or dash ‘-‘ as a separator. These are all un-winnable discussions among your friends and colleagues. Side Note: What is critical for any business is there is a well-defined and enforced standard, no matter what that standard it.

I have while scripting in Bash always used underscore ‘_’, for commands or internal functions. I have probably taken on this because environment variables have IMO always used underscore, e.g. looking at my laptop now I have for example (TERM_PROGRAM, TEE_HOME, AWS_DEFAULT_REGION).

However in recent months I have changed my coding practices within scripting to always using the dash ‘-‘. What was list_clusters, became list-clusters for example.

Why? There is just one reason; the bane of millions of effective typists and coders; the QWERTY keyboard. The dash ‘-‘ requires the use of just one finger, while the underscore requires two.

Sometimes the simpler solution is well simpler.

Loops in shell scripting

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If you are die hard Bourne Shell (/bin/sh) scripter, it can be a challenge not to be enticed by the syntax niceties of the Born Again Borne Shell (/bin/bash).

One example is the {..} syntax 

#!/bin/bash
for I in {0..5}
do
   echo $I
done

0
1
2
3
4
5

This syntax is not valid in /bin/sh on Linux.

#!/bin/sh
for I in {0..5}
do
   echo $I
done

{0..5}

NOTE: However apparently it does work in Mac OS X, which is derived from BSD, not Linux.

/bin/sh gives you a for loop but it requires the full list of iterated values instead of a range.

#!/bin/sh

for I in 0 1 2 3 4 5
do
  echo $I
done

Note: Passing a string does not work by default.

#!/bin/sh

for I in "0 1 2 3 4 5"
do
  echo $I
done

The approach to product the same result requires some format management.

#!/bin/sh

OIFS=$IFS
IFS=" "
for I in `echo "0 1 2 3 4 5"`
do
  echo $I
done
IFS=$OIFS

You can use while

#!/bin/sh

I=0
while [ $I -le 5 ]
do 
  echo $I
  I=`expr $I + 1`
done

You can use one of several other shell commands, in this example awk

#!/bin/sh

for I in `awk 'BEGIN{for (i=0;i<=5;i++) print i}'`
do 
  echo $I
done

Or, the function specifically design for sequences of numbers seq

#!/bin/sh

for I in `seq 0 5`
do 
  echo $I
done

And for these few examples, there will be more possibilities to achieve close to feature parity of the /bin/bash syntax.
An example found on BSD is jot - 0 5. This is not available Ubuntu by default but installed with the athena-jot package. However the syntax is then different for correct usage.