Could PATH contain newlines?
It is known that a path could contain newlines in any of its components.
Should we conclude then that the environment variable $PATH could contain newlines ?
If so, how to split the $PATH into its elements, similar to (Bourne like):
IFS=':' ; set -f
for var in $PATH
do
echo "<$var>"
done
But if it could be done without changing IFS, even better.
shell path newlines
edited 32 mins ago
ilkkachu
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
add a comment |
It is known that a path could contain newlines in any of its components.
Should we conclude then that the environment variable $PATH could contain newlines ?
If so, how to split the $PATH into its elements, similar to (Bourne like):
IFS=':' ; set -f
for var in $PATH
do
echo "<$var>"
done
But if it could be done without changing IFS, even better.
shell path newlines
edited 32 mins ago
ilkkachu
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
add a comment |
It is known that a path could contain newlines in any of its components.
Should we conclude then that the environment variable $PATH could contain newlines ?
If so, how to split the $PATH into its elements, similar to (Bourne like):
IFS=':' ; set -f
for var in $PATH
do
echo "<$var>"
done
But if it could be done without changing IFS, even better.
shell path newlines
edited 32 mins ago
ilkkachu
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
It is known that a path could contain newlines in any of its components.
Should we conclude then that the environment variable $PATH could contain newlines ?
If so, how to split the $PATH into its elements, similar to (Bourne like):
IFS=':' ; set -f
for var in $PATH
do
echo "<$var>"
done
But if it could be done without changing IFS, even better.
shell path newlines
shell path newlines
edited 32 mins ago
ilkkachu
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
edited 32 mins ago
ilkkachu
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
edited 32 mins ago
ilkkachu
55.9k784155
edited 32 mins ago
ilkkachu
55.9k784155
edited 32 mins ago
ilkkachu
55.9k784155
55.9k784155
asked 4 hours ago
Isaac
11.2k11648
asked 4 hours ago
Isaac
11.2k11648
asked 4 hours ago
Isaac
11.2k11648
11.2k11648
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
Yes, PATH can contain newlines (even on ancient Unix system).
As to splitting any string in shell, the only way you can do it portably is with IFS. You can use IFS=:; set -f -- $PATH or pass it to a function instead of looping with for, though.
With bash you can "read" a string into an array (mapfile -td: <<< "$PATH" path). But using arrays is usually not a good idea, because they can't be stored transparently in environment variables or passed as a single argument to external commands.
edited 41 mins ago
ilkkachu
55.9k784155
answered 1 hour ago
pizdelect
35916
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need theset -fto take effect before the$PATHexpansion. So it should beset -o noglob; set -- $PATH""
– Stéphane Chazelas
30 mins ago
Thatmapfile -td: <<< "$PATH"adds a trailing newline to the last element (and needs bash 4.4 or above).
– Stéphane Chazelas
29 mins ago
add a comment |
In POSIX shells, $IFS is a field delimiter, not separator, so a $PATH value like /bin:/usr/bin: would be split into /bin and /usr/bin instead of /bin, /usr/bin and the empty string (meaning the current directory). You need:
IFS=:; set -o noglob
for var in $PATH""; do
printf '<%s>n' "$var"
done
To avoid modifying global settings, you can use a shell with explicit splitting operators like zsh:
for var in "${(s/:/@)PATH}"; do
printf '<%s>n' "$var"
done
Though in that case, zsh already has the $path array tied to $PATH like in csh/tcsh, so:
for var in "$path[@]"; do
printf '<%s>n' "$var"
done
answered 25 mins ago
Stéphane Chazelas
299k54564913
add a comment |
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2 Answers
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oldest
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2 Answers
2
active
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votes
Yes, PATH can contain newlines (even on ancient Unix system).
As to splitting any string in shell, the only way you can do it portably is with IFS. You can use IFS=:; set -f -- $PATH or pass it to a function instead of looping with for, though.
With bash you can "read" a string into an array (mapfile -td: <<< "$PATH" path). But using arrays is usually not a good idea, because they can't be stored transparently in environment variables or passed as a single argument to external commands.
edited 41 mins ago
ilkkachu
55.9k784155
answered 1 hour ago
pizdelect
35916
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need theset -fto take effect before the$PATHexpansion. So it should beset -o noglob; set -- $PATH""
– Stéphane Chazelas
30 mins ago
Thatmapfile -td: <<< "$PATH"adds a trailing newline to the last element (and needs bash 4.4 or above).
– Stéphane Chazelas
29 mins ago
add a comment |
Yes, PATH can contain newlines (even on ancient Unix system).
As to splitting any string in shell, the only way you can do it portably is with IFS. You can use IFS=:; set -f -- $PATH or pass it to a function instead of looping with for, though.
With bash you can "read" a string into an array (mapfile -td: <<< "$PATH" path). But using arrays is usually not a good idea, because they can't be stored transparently in environment variables or passed as a single argument to external commands.
edited 41 mins ago
ilkkachu
55.9k784155
answered 1 hour ago
pizdelect
35916
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need theset -fto take effect before the$PATHexpansion. So it should beset -o noglob; set -- $PATH""
– Stéphane Chazelas
30 mins ago
Thatmapfile -td: <<< "$PATH"adds a trailing newline to the last element (and needs bash 4.4 or above).
– Stéphane Chazelas
29 mins ago
add a comment |
Yes, PATH can contain newlines (even on ancient Unix system).
As to splitting any string in shell, the only way you can do it portably is with IFS. You can use IFS=:; set -f -- $PATH or pass it to a function instead of looping with for, though.
With bash you can "read" a string into an array (mapfile -td: <<< "$PATH" path). But using arrays is usually not a good idea, because they can't be stored transparently in environment variables or passed as a single argument to external commands.
edited 41 mins ago
ilkkachu
55.9k784155
answered 1 hour ago
pizdelect
35916
Yes, PATH can contain newlines (even on ancient Unix system).
As to splitting any string in shell, the only way you can do it portably is with IFS. You can use IFS=:; set -f -- $PATH or pass it to a function instead of looping with for, though.
With bash you can "read" a string into an array (mapfile -td: <<< "$PATH" path). But using arrays is usually not a good idea, because they can't be stored transparently in environment variables or passed as a single argument to external commands.
edited 41 mins ago
ilkkachu
55.9k784155
answered 1 hour ago
pizdelect
35916
edited 41 mins ago
ilkkachu
55.9k784155
edited 41 mins ago
ilkkachu
55.9k784155
edited 41 mins ago
ilkkachu
55.9k784155
55.9k784155
answered 1 hour ago
pizdelect
35916
answered 1 hour ago
pizdelect
35916
answered 1 hour ago
pizdelect
35916
35916
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need theset -fto take effect before the$PATHexpansion. So it should beset -o noglob; set -- $PATH""
– Stéphane Chazelas
30 mins ago
Thatmapfile -td: <<< "$PATH"adds a trailing newline to the last element (and needs bash 4.4 or above).
– Stéphane Chazelas
29 mins ago
add a comment |
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need theset -fto take effect before the$PATHexpansion. So it should beset -o noglob; set -- $PATH""
– Stéphane Chazelas
30 mins ago
Thatmapfile -td: <<< "$PATH"adds a trailing newline to the last element (and needs bash 4.4 or above).
– Stéphane Chazelas
29 mins ago
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
Using arrays is often an excellent idea, as a number of answers here on unix.SE show. It's almost impossible to handle lists of strings with arbitrary data without using an array. You only need lists of paths with whitespace, or a list of command arguments to get the issue. Of course you can use the positional parameters instead of an array, but those aren't any better regarding the points you mention: they can't be sanely pushed through the environment, nor passed as a single argument to external commands.
– ilkkachu
38 mins ago
No, you need the
set -f to take effect before the $PATH expansion. So it should be set -o noglob; set -- $PATH""– Stéphane Chazelas
30 mins ago
No, you need the
set -f to take effect before the $PATH expansion. So it should be set -o noglob; set -- $PATH""– Stéphane Chazelas
30 mins ago
That
mapfile -td: <<< "$PATH" adds a trailing newline to the last element (and needs bash 4.4 or above).– Stéphane Chazelas
29 mins ago
That
mapfile -td: <<< "$PATH" adds a trailing newline to the last element (and needs bash 4.4 or above).– Stéphane Chazelas
29 mins ago
add a comment |
In POSIX shells, $IFS is a field delimiter, not separator, so a $PATH value like /bin:/usr/bin: would be split into /bin and /usr/bin instead of /bin, /usr/bin and the empty string (meaning the current directory). You need:
IFS=:; set -o noglob
for var in $PATH""; do
printf '<%s>n' "$var"
done
To avoid modifying global settings, you can use a shell with explicit splitting operators like zsh:
for var in "${(s/:/@)PATH}"; do
printf '<%s>n' "$var"
done
Though in that case, zsh already has the $path array tied to $PATH like in csh/tcsh, so:
for var in "$path[@]"; do
printf '<%s>n' "$var"
done
answered 25 mins ago
Stéphane Chazelas
299k54564913
add a comment |
In POSIX shells, $IFS is a field delimiter, not separator, so a $PATH value like /bin:/usr/bin: would be split into /bin and /usr/bin instead of /bin, /usr/bin and the empty string (meaning the current directory). You need:
IFS=:; set -o noglob
for var in $PATH""; do
printf '<%s>n' "$var"
done
To avoid modifying global settings, you can use a shell with explicit splitting operators like zsh:
for var in "${(s/:/@)PATH}"; do
printf '<%s>n' "$var"
done
Though in that case, zsh already has the $path array tied to $PATH like in csh/tcsh, so:
for var in "$path[@]"; do
printf '<%s>n' "$var"
done
answered 25 mins ago
Stéphane Chazelas
299k54564913
add a comment |
In POSIX shells, $IFS is a field delimiter, not separator, so a $PATH value like /bin:/usr/bin: would be split into /bin and /usr/bin instead of /bin, /usr/bin and the empty string (meaning the current directory). You need:
IFS=:; set -o noglob
for var in $PATH""; do
printf '<%s>n' "$var"
done
To avoid modifying global settings, you can use a shell with explicit splitting operators like zsh:
for var in "${(s/:/@)PATH}"; do
printf '<%s>n' "$var"
done
Though in that case, zsh already has the $path array tied to $PATH like in csh/tcsh, so:
for var in "$path[@]"; do
printf '<%s>n' "$var"
done
answered 25 mins ago
Stéphane Chazelas
299k54564913
In POSIX shells, $IFS is a field delimiter, not separator, so a $PATH value like /bin:/usr/bin: would be split into /bin and /usr/bin instead of /bin, /usr/bin and the empty string (meaning the current directory). You need:
IFS=:; set -o noglob
for var in $PATH""; do
printf '<%s>n' "$var"
done
To avoid modifying global settings, you can use a shell with explicit splitting operators like zsh:
for var in "${(s/:/@)PATH}"; do
printf '<%s>n' "$var"
done
Though in that case, zsh already has the $path array tied to $PATH like in csh/tcsh, so:
for var in "$path[@]"; do
printf '<%s>n' "$var"
done
answered 25 mins ago
Stéphane Chazelas
299k54564913
answered 25 mins ago
Stéphane Chazelas
299k54564913
answered 25 mins ago
Stéphane Chazelas
299k54564913
answered 25 mins ago
Stéphane Chazelas
299k54564913
299k54564913
add a comment |
add a comment |
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