Mixing
Here string adds line break
It seems that here string is adding line break. Is there a convenient way of removing it?
$ string='test'
$ echo -n $string | md5sum
098f6bcd4621d373cade4e832627b4f6 -
$ echo $string | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 -
$ md5sum <<<"$string"
d8e8fca2dc0f896fd7cb4cb0031ba249 -
bash herestring
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
add a comment |
It seems that here string is adding line break. Is there a convenient way of removing it?
$ string='test'
$ echo -n $string | md5sum
098f6bcd4621d373cade4e832627b4f6 -
$ echo $string | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 -
$ md5sum <<<"$string"
d8e8fca2dc0f896fd7cb4cb0031ba249 -
bash herestring
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
1
<<<also adds trailing newlines
– Ian2thedv
Jun 9 '16 at 14:30
add a comment |
It seems that here string is adding line break. Is there a convenient way of removing it?
$ string='test'
$ echo -n $string | md5sum
098f6bcd4621d373cade4e832627b4f6 -
$ echo $string | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 -
$ md5sum <<<"$string"
d8e8fca2dc0f896fd7cb4cb0031ba249 -
bash herestring
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
It seems that here string is adding line break. Is there a convenient way of removing it?
$ string='test'
$ echo -n $string | md5sum
098f6bcd4621d373cade4e832627b4f6 -
$ echo $string | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 -
$ md5sum <<<"$string"
d8e8fca2dc0f896fd7cb4cb0031ba249 -
bash herestring
bash herestring
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
edited Jun 9 '16 at 14:39
fedorqui
165k51332377
165k51332377
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
asked Jun 9 '16 at 14:24
NarūnasK
1,42831533
1,42831533
1
<<<also adds trailing newlines
– Ian2thedv
Jun 9 '16 at 14:30
add a comment |
1
<<<also adds trailing newlines
– Ian2thedv
Jun 9 '16 at 14:30
1
1
<<< also adds trailing newlines– Ian2thedv
Jun 9 '16 at 14:30
<<< also adds trailing newlines– Ian2thedv
Jun 9 '16 at 14:30
add a comment |
3 Answers
3
active
oldest
votes
Yes, you are right: <<< adds a trailing new line.
You can see it with:
$ cat - <<< "hello" | od -c
0000000 h e l l o n
0000006
Let's compare this with the other approaches:
$ echo "hello" | od -c
0000000 h e l l o n
0000006
$ echo -n "hello" | od -c
0000000 h e l l o
0000005
$ printf "hello" | od -c
0000000 h e l l o
0000005
So we have the table:
| adds new line |
-------------------------|
printf | No |
echo -n | No |
echo | Yes |
<<< | Yes |
From Why does a bash here-string add a trailing newline char?:
Most commands expect text input. In the unix world, a text file
consists of a sequence of lines, each ending in a
newline.
So in most cases a final newline is required. An especially common
case is to grab the output of a command with a command susbtitution,
process it in some way, then pass it to another command. The command
substitution strips final newlines;<<<puts one back.
edited Apr 13 '17 at 12:36
Community♦
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
add a comment |
fedorqui's helpful answer shows that and why here-strings (and also here-documents) invariably append a newline.
As for:
Is there a convenient way of removing it?
In Bash, use printf inside a process substitution as an "n-less" alternative to a here-string:
... < <(printf %s ...)
Applied to your example:
$ md5sum < <(printf %s 'test')
098f6bcd4621d373cade4e832627b4f6
Alternatively, as user202729 suggests, simply use printf %s in the pipeline, which has the added advantage of not only using a more familiar feature but also making the command work in (more strictly) POSIX-compliant shells (in scripts targeting /bin/sh):
$ printf %s 'test' | md5sum
098f6bcd4621d373cade4e832627b4f6
answered Jun 10 '16 at 23:07
mklement0
126k20240268
add a comment |
As a "here doc" add a newline:
$ string="hello test"
$ cat <<_test_ | xxd
> $string
> _test_
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Also a "here string" does:
$ cat <<<"$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Probably the easiest solution to get an string non-ending on newline would be printf:
$ printf '%s' "$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 hello test
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, you are right: <<< adds a trailing new line.
You can see it with:
$ cat - <<< "hello" | od -c
0000000 h e l l o n
0000006
Let's compare this with the other approaches:
$ echo "hello" | od -c
0000000 h e l l o n
0000006
$ echo -n "hello" | od -c
0000000 h e l l o
0000005
$ printf "hello" | od -c
0000000 h e l l o
0000005
So we have the table:
| adds new line |
-------------------------|
printf | No |
echo -n | No |
echo | Yes |
<<< | Yes |
From Why does a bash here-string add a trailing newline char?:
Most commands expect text input. In the unix world, a text file
consists of a sequence of lines, each ending in a
newline.
So in most cases a final newline is required. An especially common
case is to grab the output of a command with a command susbtitution,
process it in some way, then pass it to another command. The command
substitution strips final newlines;<<<puts one back.
edited Apr 13 '17 at 12:36
Community♦
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
add a comment |
Yes, you are right: <<< adds a trailing new line.
You can see it with:
$ cat - <<< "hello" | od -c
0000000 h e l l o n
0000006
Let's compare this with the other approaches:
$ echo "hello" | od -c
0000000 h e l l o n
0000006
$ echo -n "hello" | od -c
0000000 h e l l o
0000005
$ printf "hello" | od -c
0000000 h e l l o
0000005
So we have the table:
| adds new line |
-------------------------|
printf | No |
echo -n | No |
echo | Yes |
<<< | Yes |
From Why does a bash here-string add a trailing newline char?:
Most commands expect text input. In the unix world, a text file
consists of a sequence of lines, each ending in a
newline.
So in most cases a final newline is required. An especially common
case is to grab the output of a command with a command susbtitution,
process it in some way, then pass it to another command. The command
substitution strips final newlines;<<<puts one back.
edited Apr 13 '17 at 12:36
Community♦
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
add a comment |
Yes, you are right: <<< adds a trailing new line.
You can see it with:
$ cat - <<< "hello" | od -c
0000000 h e l l o n
0000006
Let's compare this with the other approaches:
$ echo "hello" | od -c
0000000 h e l l o n
0000006
$ echo -n "hello" | od -c
0000000 h e l l o
0000005
$ printf "hello" | od -c
0000000 h e l l o
0000005
So we have the table:
| adds new line |
-------------------------|
printf | No |
echo -n | No |
echo | Yes |
<<< | Yes |
From Why does a bash here-string add a trailing newline char?:
Most commands expect text input. In the unix world, a text file
consists of a sequence of lines, each ending in a
newline.
So in most cases a final newline is required. An especially common
case is to grab the output of a command with a command susbtitution,
process it in some way, then pass it to another command. The command
substitution strips final newlines;<<<puts one back.
edited Apr 13 '17 at 12:36
Community♦
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
Yes, you are right: <<< adds a trailing new line.
You can see it with:
$ cat - <<< "hello" | od -c
0000000 h e l l o n
0000006
Let's compare this with the other approaches:
$ echo "hello" | od -c
0000000 h e l l o n
0000006
$ echo -n "hello" | od -c
0000000 h e l l o
0000005
$ printf "hello" | od -c
0000000 h e l l o
0000005
So we have the table:
| adds new line |
-------------------------|
printf | No |
echo -n | No |
echo | Yes |
<<< | Yes |
From Why does a bash here-string add a trailing newline char?:
Most commands expect text input. In the unix world, a text file
consists of a sequence of lines, each ending in a
newline.
So in most cases a final newline is required. An especially common
case is to grab the output of a command with a command susbtitution,
process it in some way, then pass it to another command. The command
substitution strips final newlines;<<<puts one back.
edited Apr 13 '17 at 12:36
Community♦
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
edited Apr 13 '17 at 12:36
Community♦
11
edited Apr 13 '17 at 12:36
Community♦
11
edited Apr 13 '17 at 12:36
Community♦
11
11
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
answered Jun 9 '16 at 14:35
fedorqui
165k51332377
165k51332377
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
add a comment |
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
2
2
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
Also, note that a here-string is a shortcut for a single-line here document, which always ends with a newline.
– chepner
Jun 9 '16 at 15:03
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
@chepner this is an interesting point I wasn't aware of, that in fact may be relevant for this discussion on Here documents in documentation beta
– fedorqui
Jun 9 '16 at 16:26
add a comment |
fedorqui's helpful answer shows that and why here-strings (and also here-documents) invariably append a newline.
As for:
Is there a convenient way of removing it?
In Bash, use printf inside a process substitution as an "n-less" alternative to a here-string:
... < <(printf %s ...)
Applied to your example:
$ md5sum < <(printf %s 'test')
098f6bcd4621d373cade4e832627b4f6
Alternatively, as user202729 suggests, simply use printf %s in the pipeline, which has the added advantage of not only using a more familiar feature but also making the command work in (more strictly) POSIX-compliant shells (in scripts targeting /bin/sh):
$ printf %s 'test' | md5sum
098f6bcd4621d373cade4e832627b4f6
answered Jun 10 '16 at 23:07
mklement0
126k20240268
add a comment |
fedorqui's helpful answer shows that and why here-strings (and also here-documents) invariably append a newline.
As for:
Is there a convenient way of removing it?
In Bash, use printf inside a process substitution as an "n-less" alternative to a here-string:
... < <(printf %s ...)
Applied to your example:
$ md5sum < <(printf %s 'test')
098f6bcd4621d373cade4e832627b4f6
Alternatively, as user202729 suggests, simply use printf %s in the pipeline, which has the added advantage of not only using a more familiar feature but also making the command work in (more strictly) POSIX-compliant shells (in scripts targeting /bin/sh):
$ printf %s 'test' | md5sum
098f6bcd4621d373cade4e832627b4f6
answered Jun 10 '16 at 23:07
mklement0
126k20240268
add a comment |
fedorqui's helpful answer shows that and why here-strings (and also here-documents) invariably append a newline.
As for:
Is there a convenient way of removing it?
In Bash, use printf inside a process substitution as an "n-less" alternative to a here-string:
... < <(printf %s ...)
Applied to your example:
$ md5sum < <(printf %s 'test')
098f6bcd4621d373cade4e832627b4f6
Alternatively, as user202729 suggests, simply use printf %s in the pipeline, which has the added advantage of not only using a more familiar feature but also making the command work in (more strictly) POSIX-compliant shells (in scripts targeting /bin/sh):
$ printf %s 'test' | md5sum
098f6bcd4621d373cade4e832627b4f6
answered Jun 10 '16 at 23:07
mklement0
126k20240268
fedorqui's helpful answer shows that and why here-strings (and also here-documents) invariably append a newline.
As for:
Is there a convenient way of removing it?
In Bash, use printf inside a process substitution as an "n-less" alternative to a here-string:
... < <(printf %s ...)
Applied to your example:
$ md5sum < <(printf %s 'test')
098f6bcd4621d373cade4e832627b4f6
Alternatively, as user202729 suggests, simply use printf %s in the pipeline, which has the added advantage of not only using a more familiar feature but also making the command work in (more strictly) POSIX-compliant shells (in scripts targeting /bin/sh):
$ printf %s 'test' | md5sum
098f6bcd4621d373cade4e832627b4f6
answered Jun 10 '16 at 23:07
mklement0
126k20240268
edited Jun 24 '18 at 12:39
answered Jun 10 '16 at 23:07
mklement0
126k20240268
answered Jun 10 '16 at 23:07
mklement0
126k20240268
answered Jun 10 '16 at 23:07
mklement0
126k20240268
126k20240268
add a comment |
add a comment |
As a "here doc" add a newline:
$ string="hello test"
$ cat <<_test_ | xxd
> $string
> _test_
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Also a "here string" does:
$ cat <<<"$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Probably the easiest solution to get an string non-ending on newline would be printf:
$ printf '%s' "$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 hello test
add a comment |
As a "here doc" add a newline:
$ string="hello test"
$ cat <<_test_ | xxd
> $string
> _test_
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Also a "here string" does:
$ cat <<<"$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Probably the easiest solution to get an string non-ending on newline would be printf:
$ printf '%s' "$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 hello test
add a comment |
As a "here doc" add a newline:
$ string="hello test"
$ cat <<_test_ | xxd
> $string
> _test_
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Also a "here string" does:
$ cat <<<"$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Probably the easiest solution to get an string non-ending on newline would be printf:
$ printf '%s' "$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 hello test
As a "here doc" add a newline:
$ string="hello test"
$ cat <<_test_ | xxd
> $string
> _test_
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Also a "here string" does:
$ cat <<<"$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 0a hello test.
Probably the easiest solution to get an string non-ending on newline would be printf:
$ printf '%s' "$string" | xxd
0000000: 6865 6c6c 6f20 7465 7374 hello test
answered Jun 10 '16 at 22:21
user2350426
add a comment |
add a comment |
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<<<also adds trailing newlines– Ian2thedv
Jun 9 '16 at 14:30