Safex provides a safe way to do the equivalent of bash parameter expansion without the risk of undesired interpretation by the shell of string contents.
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Safex allows literals to be injected into literals, avoiding the need for double quoting. This reduces the need to escape and take other convoluted precautions in order to protect text from interference by the shell. "Safe" in this context means 'safe from interpretation' by the shell causing wayward expansions, variable and command substitutions, globbing, brace expansions, tilde expansions, case modification, etc.
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It makes string manipulation and parameter passing more similar to the dominant paradigm used in programming languages, following the familiar pattern:
<Template with Embedded Arguments Placeholders {1} {2} {3}>,<Value of Argument {1}>,<Value of {2}>,<Value of {3}>...This pattern is seen in C#'s
Console.WriteLineand is common to many programming languages. -
Safex can be used to rearrange the order of parameters to allow more frequent use of bash aliases, especially when expressions require that the text or parameters provided after an alias (i.e.,
myalias <myarg> <mytext>) be located somewhere else than at the very end of the line. -
Note that more recent versions of Safex can return an
evalcommand string that is executed by a bash wrapper function within a bash script. This is quite powerful, though clearly not at all 'safe'! Much of the documentation herein needs to be updated to reflect this change, which should be controlled by a command line switch to make the behaviour optional.
safex templateString value1 [value2...]Example with two parameters and special characters:
output=$(./safex $'My dog\'s name is {0} and my cat\'s name is {1}' 'Fido' 'Whiskers')
eval "$output"Example with three parameters, special characters, and the need for complex escaping:
output=$(./safex $'Here are the names: {0}, {1}, and {2}' 'Fido' 'Whiskers' 'Tweety')
eval "$output"` Example using variables:
output=$(./safex "$template" "$param1" "$param2")
eval "$output"` To execute the returned string (not necessary since recent changes):
local temp_file=$(mktemp)
/usr/bin/safex "${args[@]}" > "$temp_file"
echo -en "executing: "; cat "$temp_file"; echo
sudo /usr/bin/unbuffer bash -c 'USER=root; ' "$(cat "$temp_file")" | more` The code in this project is licensed under the MIT License. This means you can freely use, modify, distribute, and sell it under the same license.
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