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30 lines
1.1 KiB
30 lines
1.1 KiB
2 years ago
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#!/bin/sh
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echo "This spell will teach you the basics of the eval and exec functions in POSIX-compliant Bash"
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echo "To study the code of the examples, please use the command: cat 11_eval.sh"
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# eval function
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# The eval function takes a string as an argument and treats it as if it were a command.
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# It allows the user to dynamically generate and execute commands.
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# Example 1: Using variables in a command
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ingredient="Dragon's blood"
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eval "echo Gathering ingredients for the potion: $ingredient"
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# Example 2: Using command substitution
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eval "echo Today is $(date)"
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# Example 3: Using multiple commands
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eval "echo Starting spell; sleep 2; echo Spell complete"
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# exec function
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# The exec function also takes a command as its argument, but it replaces the current shell process with the new command.
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# This means that the new command will not run in a subshell and any changes made by the new command will affect the current shell.
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# Example 1: Using exec to run a new shell
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exec /bin/sh
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# Example 2: Using exec to run a command
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exec echo "This command is being run by exec"
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echo "Spell cast successfully"
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