54 lines
1.2 KiB
Markdown
54 lines
1.2 KiB
Markdown
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---
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categories:
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- Programming Languages
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tags:
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- shell
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---
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# Conditionals in Bash
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## If statements
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- Conditional blocks start with `if` and end with the inversion `fi` (this is a common syntactic pattern in bash)
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- The conditional expression must be placed in square brackets with spaces either side. The spaces matter: if you omit them, the code will not run
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- We designate the code to run when the conditional is met with `then`
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- We can incorporate else if logic with `elif`
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## Basic example
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```bash
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if [ -e $var ]; then
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# Do something
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else
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# Do something else
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fi
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```
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## If, else
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```bash
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if [ "$myMove" -eq "$opponentMove" ]; then
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(( totalScore+=myMove+3 ))
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elif [ $absDiff -eq 2 ] && [ "$myMove" -gt "$opponentMove" ]; then
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(( totalScore+=myMove))
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elif [ $absDiff -eq 2 ] && [ "$opponentMove" -gt "$myMove" ]; then
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(( totalScore+=myMove+6))
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elif [ $absDiff -eq 1 ] && [ "$opponentMove" -gt "$myMove" ]; then
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(( totalScore+=myMove))
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elif [ $absDiff -eq 1 ] && [ "$myMove" -gt "$opponentMove" ]; then
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(( totalScore+=myMove+6))
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fi
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```
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## Nested conditionals
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```bash
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if [[ "$line" =~ ^$ ]]; then
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if [[ "$runningTotal" -gt "$highest" ]]; then
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(( highest=runningTotal ))
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fi
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# Reset running sum
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(( runningTotal=0 ))
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fi
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```
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