name: "IFS"
cases:
- name: "Default IFS value"
stdin: |
# Default IFS is space, tab, newline
[[ "$IFS" == $' \t\n' ]] && echo "IFS has default value"
- name: "Field splitting with default IFS"
stdin: |
var="one two three
four"
echo "Fields:" $var
- name: "Field splitting with custom single-char IFS"
stdin: |
IFS=':'
var="one:two:three"
echo $var
- name: "Field splitting with multi-char IFS"
stdin: |
IFS=':,'
var="one:two,three:four"
echo $var
- name: "Empty IFS disables field splitting"
stdin: |
IFS=''
var="one two three"
echo "[$var]"
# Should print with all whitespace preserved
- name: "Empty IFS with expansion"
stdin: |
IFS=''
var="a b c"
set -- $var
echo "Count: $#"
echo "[$1]"
- name: "Unset IFS uses default splitting"
stdin: |
unset IFS
var="one two three"
echo $var
- name: "IFS whitespace vs non-whitespace splitting"
known_failure: true
stdin: |
# Non-whitespace IFS chars create empty fields
IFS=':'
var=":one::two:"
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "IFS whitespace splitting ignores leading/trailing"
stdin: |
# Whitespace IFS chars ignore leading/trailing
IFS=' '
var=" one two "
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "Mixed whitespace and non-whitespace IFS"
stdin: |
IFS=' :'
var="one:two three : four"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "Mixed IFS leading non-whitespace"
known_failure: true
stdin: |
IFS=': '
var=":one: :two"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "Mixed IFS trailing non-whitespace"
stdin: |
IFS=' :'
var="one :two: "
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS only whitespace multiple chars"
stdin: |
IFS=$' \t'
var=" one two three "
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "IFS only non-whitespace multiple chars"
known_failure: true
stdin: |
IFS=':,'
var=":,one,:,two,:"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS only tab character"
stdin: |
IFS=$'\t'
var=" a b "
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "IFS only newline character"
stdin: |
IFS=$'\n'
var="
a
b
"
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "IFS affects command substitution"
stdin: |
IFS=':'
result=$(echo "a:b:c")
# Command substitution itself doesn't split, but expansion does
set -- $result
echo "$#"
echo "$@"
- name: "IFS with command substitution multiline"
stdin: |
IFS=$'\n'
result=$(printf "a\nb\nc")
set -- $result
echo "Count: $#"
echo "$1|$2|$3"
- name: "IFS affects arithmetic expansion"
stdin: |
IFS=' '
# Arithmetic expansion result is splittable
set -- $((1 + 1)) $((2 + 2))
echo "Count: $#"
echo "$@"
- name: "IFS in array expansion"
stdin: |
arr=(one two three)
IFS=':'
echo "${arr[*]}"
# With $* should join with first char of IFS
- name: "IFS with $* vs $@"
stdin: |
set -- one two three
IFS=':'
echo "$*"
echo "$@"
- name: "IFS with $* unquoted"
stdin: |
set -- "a:b" "c:d"
IFS=':'
# Unquoted $* joins then splits
set -- $*
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS null char handling"
stdin: |
IFS=':'
var=""
set -- $var
echo "Empty var count: $#"
- name: "IFS preservation across commands"
stdin: |
IFS=':'
echo "First: $IFS"
var="a:b"
echo $var
echo "After: $IFS"
- name: "IFS in subshell"
stdin: |
IFS=':'
(
echo "In subshell: [$IFS]"
var="a:b:c"
set -- $var
echo "Count: $#"
)
echo "Parent: [$IFS]"
- name: "IFS local to command"
stdin: |
var="a:b:c"
IFS=':' echo $var
# IFS assignment should only affect that command
echo "After: [$IFS]"
- name: "IFS does not affect for loop literal words"
known_failure: true
stdin: |
IFS=':'
for word in a:b:c; do
echo "[$word]"
done
- name: "IFS affects for loop variable expansion"
stdin: |
IFS=':'
var="a:b:c"
for word in $var; do
echo "[$word]"
done
- name: "IFS affects for loop command substitution"
stdin: |
IFS=':'
for word in $(echo "x:y:z"); do
echo "[$word]"
done
- name: "IFS with quoted vs unquoted expansion"
stdin: |
IFS=':'
var="a:b:c"
echo "Unquoted:" $var
echo "Quoted: $var"
- name: "IFS with partially quoted expansion"
known_failure: true
stdin: |
IFS=':'
var="a:b:c"
set -- "$var":more
echo "Count: $#"
echo "$@"
- name: "IFS whitespace sequence handling"
stdin: |
IFS=' '
var="a b"
set -- $var
echo "Count: $#"
echo "Args: $@"
- name: "IFS non-whitespace sequence handling"
known_failure: true
stdin: |
IFS=':'
var="a::::b"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS with parameter expansion"
stdin: |
IFS=':'
var="a:b:c"
result=${var}
set -- $result
echo "$#"
echo "$@"
- name: "IFS with parameter expansion default value"
stdin: |
IFS=':'
set -- ${unset:-a:b:c}
echo "Count: $#"
echo "$@"
- name: "IFS with parameter expansion empty default"
stdin: |
IFS=':'
set -- ${unset:-}
echo "Count: $#"
- name: "IFS with parameter length"
stdin: |
IFS=':'
var="a:b:c"
# Length expansion returns a number, not subject to further splitting
len=${#var}
set -- $len
echo "Count: $#"
echo "[$1]"
- name: "IFS with glob pattern literal"
known_failure: true
stdin: |
IFS=':'
# Glob patterns as literals shouldn't split
for word in *.txt:*.sh; do
echo "[$word]"
done
- name: "IFS newline handling"
stdin: |
IFS=$'\n'
var="a
b
c"
set -- $var
echo "Count: $#"
echo "$1|$2|$3"
- name: "IFS tab handling"
stdin: |
IFS=$'\t'
var="a b c"
set -- $var
echo "Count: $#"
echo "$1|$2|$3"
- name: "IFS with backslash in value"
stdin: |
IFS=':'
var='a\:b:c\:d'
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS first char for joining"
stdin: |
set -- a b c
IFS=':'
# First char of IFS used for $* joining
result="$*"
echo "[$result]"
- name: "IFS first char empty IFS"
known_failure: true
stdin: |
set -- a b c
IFS=''
result="$*"
echo "[$result]"
- name: "IFS multiple whitespace at start"
stdin: |
IFS=' '
var=" a b"
set -- $var
echo "Count: $#"
echo "$@"
- name: "IFS multiple whitespace at end"
stdin: |
IFS=' '
var="a b "
set -- $var
echo "Count: $#"
echo "$@"
- name: "IFS with read builtin integration"
stdin: |
IFS=':'
echo "a:b:c" | (read x y z; echo "x=[$x] y=[$y] z=[$z]")
- name: "IFS whitespace before non-whitespace"
known_failure: true
stdin: |
IFS=' :'
var=" :a"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done
- name: "IFS non-whitespace before whitespace"
known_failure: true
stdin: |
IFS=': '
var=": a"
set -- $var
echo "Count: $#"
for arg in "$@"; do
echo "[$arg]"
done