# Iteration 17: Conditional Expressions [[ ]]
# === Basic conditional expressions ===
=== simple file test
[[ -f file ]]
---
(cond (cond-unary "-f" (cond-term "file")))
---
=== directory test
[[ -d /tmp ]]
---
(cond (cond-unary "-d" (cond-term "/tmp")))
---
=== string equality
[[ "$x" == "yes" ]]
---
(cond (cond-binary "==" (cond-term ""$x"") (cond-term ""yes"")))
---
=== string inequality
[[ "$x" != "no" ]]
---
(cond (cond-binary "!=" (cond-term ""$x"") (cond-term ""no"")))
---
=== string pattern match
[[ "$file" == *.txt ]]
---
(cond (cond-binary "==" (cond-term ""$file"") (cond-term "*.txt")))
---
=== regex match
[[ "$x" =~ ^[0-9]+$ ]]
---
(cond (cond-binary "=~" (cond-term ""$x"") (cond-term "^[0-9]+$")))
---
=== empty string test
[[ -z "$var" ]]
---
(cond (cond-unary "-z" (cond-term ""$var"")))
---
=== non-empty string test
[[ -n "$var" ]]
---
(cond (cond-unary "-n" (cond-term ""$var"")))
---
=== internal and operator
[[ -f file && -r file ]]
---
(cond (cond-and (cond-unary "-f" (cond-term "file")) (cond-unary "-r" (cond-term "file"))))
---
=== internal or operator
[[ -f file || -d file ]]
---
(cond (cond-or (cond-unary "-f" (cond-term "file")) (cond-unary "-d" (cond-term "file"))))
---
=== internal negation
[[ ! -f file ]]
---
(cond (cond-unary "-f" (cond-term "file")))
---
=== complex condition
[[ -f file && ! -d file ]]
---
(cond (cond-and (cond-unary "-f" (cond-term "file")) (cond-unary "-d" (cond-term "file"))))
---
=== multiple operators
[[ -f a && -f b || -f c ]]
---
(cond (cond-or (cond-and (cond-unary "-f" (cond-term "a")) (cond-unary "-f" (cond-term "b"))) (cond-unary "-f" (cond-term "c"))))
---
=== parenthesized groups
[[ ( -f a || -f b ) && -r a ]]
---
(cond (cond-and (cond-expr (cond-or (cond-unary "-f" (cond-term "a")) (cond-unary "-f" (cond-term "b")))) (cond-unary "-r" (cond-term "a"))))
---
=== if with conditional
if [[ -f file ]]; then echo exists; fi
---
(if (cond (cond-unary "-f" (cond-term "file"))) (command (word "echo") (word "exists")))
---
=== while with conditional
while [[ -f lockfile ]]; do sleep 1; done
---
(while (cond (cond-unary "-f" (cond-term "lockfile"))) (command (word "sleep") (word "1")))
---
=== conditional in list
[[ -f file ]] && echo exists
---
(and (cond (cond-unary "-f" (cond-term "file"))) (command (word "echo") (word "exists")))
---
=== conditional with or list
[[ -f file ]] || touch file
---
(or (cond (cond-unary "-f" (cond-term "file"))) (command (word "touch") (word "file")))
---
=== negated conditional
! [[ -f file ]]
---
(negation (cond (cond-unary "-f" (cond-term "file"))))
---
=== time conditional
time [[ -f file ]]
---
(time (cond (cond-unary "-f" (cond-term "file"))))
---
=== conditional with spaces
[[ -f file ]]
---
(cond (cond-unary "-f" (cond-term "file")))
---
=== conditional with variables
[[ $a == $b ]]
---
(cond (cond-binary "==" (cond-term "$a") (cond-term "$b")))
---
=== conditional with command substitution
[[ $(whoami) == root ]]
---
(cond (cond-binary "==" (cond-term "$(whoami)") (cond-term "root")))
---
=== conditional with arithmetic
[[ $((1+1)) -eq 2 ]]
---
(cond (cond-binary "-eq" (cond-term "$((1+1))") (cond-term "2")))
---
=== string comparison operators
[[ "abc" < "def" ]]
---
(cond (cond-binary "<" (cond-term ""abc"") (cond-term ""def"")))
---
=== greater than comparison
[[ "def" > "abc" ]]
---
(cond (cond-binary ">" (cond-term ""def"") (cond-term ""abc"")))
---
=== numeric comparison
[[ $x -eq 10 ]]
---
(cond (cond-binary "-eq" (cond-term "$x") (cond-term "10")))
---
=== arithmetic in comparison
[[ $((a+b)) -gt 100 ]]
---
(cond (cond-binary "-gt" (cond-term "$((a+b))") (cond-term "100")))
---
=== regex with special chars
[[ "$path" =~ ^/home/[^/]+/\.config$ ]]
---
(cond (cond-binary "=~" (cond-term ""$path"") (cond-term "^/home/[^/]+/\.config$")))
---
=== negated condition with parens
[[ ! ( -f a && -f b ) ]]
---
(cond (cond-expr (cond-and (cond-unary "-f" (cond-term "a")) (cond-unary "-f" (cond-term "b")))))
---
=== multiple nested parens
[[ ( ( -f a ) ) ]]
---
(cond (cond-expr (cond-expr (cond-unary "-f" (cond-term "a")))))
---
=== string with embedded brackets
[[ "$x" == "[test]" ]]
---
(cond (cond-binary "==" (cond-term ""$x"") (cond-term ""[test]"")))
---
=== conditional with newline in quoted string
[[ "$x" == "line1
line2" ]]
---
(cond (cond-binary "==" (cond-term ""$x"") (cond-term ""line1
line2"")))
---
=== unquoted variable comparison
[[ $var1 == $var2 ]]
---
(cond (cond-binary "==" (cond-term "$var1") (cond-term "$var2")))
---
=== wildcard at start
[[ "$file" == *.log ]]
---
(cond (cond-binary "==" (cond-term ""$file"") (cond-term "*.log")))
---
=== wildcard at end
[[ "$file" == log.* ]]
---
(cond (cond-binary "==" (cond-term ""$file"") (cond-term "log.*")))
---
=== case insensitive pattern
[[ "${str,,}" == hello ]]
---
(cond (cond-binary "==" (cond-term ""${str,,}"") (cond-term "hello")))
---
=== conditional in pipeline
[[ -f file ]] | cat
---
(pipe (cond (cond-unary "-f" (cond-term "file"))) (command (word "cat")))
---
=== conditional with semicolon after
[[ -f file ]]; echo done
---
(semi (cond (cond-unary "-f" (cond-term "file"))) (command (word "echo") (word "done")))
---
=== hidden command sub in unary
[[ -f $(get_path) ]]
---
(cond (cond-unary "-f" (cond-term "$(get_path)")))
---
=== implicit -n for bare word
[[ $var ]]
---
(cond (cond-unary "-n" (cond-term "$var")))
---
=== process substitution in conditional
[[ -f <(echo test) ]]
---
(cond (cond-unary "-f" (cond-term "<(echo test)")))
---
=== regex with POSIX character class
[[ $x =~ [[:alpha:]] ]]
---
(cond (cond-binary "=~" (cond-term "$x") (cond-term "[[:alpha:]]")))
---
=== regex with multiple POSIX classes
[[ $x =~ [[:alpha:][:digit:]] ]]
---
(cond (cond-binary "=~" (cond-term "$x") (cond-term "[[:alpha:][:digit:]]")))
---
=== regex with negated class
[[ $x =~ [^[:space:]] ]]
---
(cond (cond-binary "=~" (cond-term "$x") (cond-term "[^[:space:]]")))
---
=== regex with literal ] as first char
[[ $x =~ []a-z] ]]
---
(cond (cond-binary "=~" (cond-term "$x") (cond-term "[]a-z]")))
---
=== unary with command substitution containing redirect
[[ -z "$(find foo 2>/dev/null)" ]]
---
(cond (cond-unary "-z" (cond-term ""$(find foo 2> /dev/null)"")))
---
=== pattern with POSIX character class
[[ x = *[[:space:]]* ]]
---
(cond (cond-binary "=" (cond-term "x") (cond-term "*[[:space:]]*")))
---
=== dollar sign followed by empty string
[[ "$LOCAL_DEV" == $"" ]]
---
(cond (cond-binary "==" (cond-term ""$LOCAL_DEV"") (cond-term """")))
---
=== regex with arithmetic expansion containing brackets
[[ ! $UserInput =~ ^[0-$((${#arr[@]}-1))] ]]
---
(cond (cond-binary "=~" (cond-term "$UserInput") (cond-term "^[0-$((${#arr[@]}-1))]")))
---