An echo operation includes some piece of text it should not include
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0
down vote
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On a WSL Ubuntu 16.04 (Xenial) with composer I executed:
echo 2 * 3 > 5 is a valid inequality
It resulted in a file by the name of 5, with the content:
2 composer-setup.php 3 is a valid inequality
I don't know why this echo includes the text composer-setup.php as well; it should have included everything from left and right besides 5 (the file name) as echo can have a single stream of text as its file name for redirection (no spaces allowed, as I understand, hence the 5 name).
Why is the composer-setup.php appears there between the 2 and 3?
shell wildcards echo
edited Dec 8 at 17:33
terdon♦
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
add a comment |
up vote
0
down vote
favorite
On a WSL Ubuntu 16.04 (Xenial) with composer I executed:
echo 2 * 3 > 5 is a valid inequality
It resulted in a file by the name of 5, with the content:
2 composer-setup.php 3 is a valid inequality
I don't know why this echo includes the text composer-setup.php as well; it should have included everything from left and right besides 5 (the file name) as echo can have a single stream of text as its file name for redirection (no spaces allowed, as I understand, hence the 5 name).
Why is the composer-setup.php appears there between the 2 and 3?
shell wildcards echo
edited Dec 8 at 17:33
terdon♦
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
On a WSL Ubuntu 16.04 (Xenial) with composer I executed:
echo 2 * 3 > 5 is a valid inequality
It resulted in a file by the name of 5, with the content:
2 composer-setup.php 3 is a valid inequality
I don't know why this echo includes the text composer-setup.php as well; it should have included everything from left and right besides 5 (the file name) as echo can have a single stream of text as its file name for redirection (no spaces allowed, as I understand, hence the 5 name).
Why is the composer-setup.php appears there between the 2 and 3?
shell wildcards echo
edited Dec 8 at 17:33
terdon♦
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
On a WSL Ubuntu 16.04 (Xenial) with composer I executed:
echo 2 * 3 > 5 is a valid inequality
It resulted in a file by the name of 5, with the content:
2 composer-setup.php 3 is a valid inequality
I don't know why this echo includes the text composer-setup.php as well; it should have included everything from left and right besides 5 (the file name) as echo can have a single stream of text as its file name for redirection (no spaces allowed, as I understand, hence the 5 name).
Why is the composer-setup.php appears there between the 2 and 3?
shell wildcards echo
shell wildcards echo
edited Dec 8 at 17:33
terdon♦
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
edited Dec 8 at 17:33
terdon♦
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
edited Dec 8 at 17:33
terdon♦
127k31246423
edited Dec 8 at 17:33
terdon♦
127k31246423
edited Dec 8 at 17:33
terdon♦
127k31246423
127k31246423
asked Dec 7 at 19:58
JohnDoea
1151132
asked Dec 7 at 19:58
JohnDoea
1151132
asked Dec 7 at 19:58
JohnDoea
1151132
1151132
add a comment |
add a comment |
2 Answers
2
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oldest
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4
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You've executed a commandline that has two shell-special characters in it: * and >. You saw what > did; the * is a wildcard / globbing character that picked up every1 file in your current directory. You have one file, named composer-setup.php in your current directory.
Quote your commandline; single-quotes work if there are no single-quotes in your text:
echo '2 * 3 > 5 is a valid inequality'
1: every file (or directory, socket, etc) that doesn't start with a period, unless you've set a shell option (such as dotglob) to specifically enable dot-file globbing.
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
add a comment |
up vote
4
down vote
There are two things happening here...
First is that the shell sees the * character and replaces it with a list of files in the current directory. This is known as "globbing"
In addition the > 5 is seen as a redirection command.
so
echo 2 * 3 > 5 is a valid inequality
Is parsed as
echo 2 * 3 is a valid inequality > 5
This results in a file called "5" being created with the contents "2 list of current files 3 is a valid inequality".
To prevent this from happening we need to use quotes
echo '2 * 3 > 5 is a valid inequality'
The '...' prevents the shell from interpreting the special characters and displays the string you entered.
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
accepted
You've executed a commandline that has two shell-special characters in it: * and >. You saw what > did; the * is a wildcard / globbing character that picked up every1 file in your current directory. You have one file, named composer-setup.php in your current directory.
Quote your commandline; single-quotes work if there are no single-quotes in your text:
echo '2 * 3 > 5 is a valid inequality'
1: every file (or directory, socket, etc) that doesn't start with a period, unless you've set a shell option (such as dotglob) to specifically enable dot-file globbing.
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
add a comment |
up vote
4
down vote
accepted
You've executed a commandline that has two shell-special characters in it: * and >. You saw what > did; the * is a wildcard / globbing character that picked up every1 file in your current directory. You have one file, named composer-setup.php in your current directory.
Quote your commandline; single-quotes work if there are no single-quotes in your text:
echo '2 * 3 > 5 is a valid inequality'
1: every file (or directory, socket, etc) that doesn't start with a period, unless you've set a shell option (such as dotglob) to specifically enable dot-file globbing.
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
add a comment |
up vote
4
down vote
accepted
up vote
4
down vote
accepted
You've executed a commandline that has two shell-special characters in it: * and >. You saw what > did; the * is a wildcard / globbing character that picked up every1 file in your current directory. You have one file, named composer-setup.php in your current directory.
Quote your commandline; single-quotes work if there are no single-quotes in your text:
echo '2 * 3 > 5 is a valid inequality'
1: every file (or directory, socket, etc) that doesn't start with a period, unless you've set a shell option (such as dotglob) to specifically enable dot-file globbing.
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
You've executed a commandline that has two shell-special characters in it: * and >. You saw what > did; the * is a wildcard / globbing character that picked up every1 file in your current directory. You have one file, named composer-setup.php in your current directory.
Quote your commandline; single-quotes work if there are no single-quotes in your text:
echo '2 * 3 > 5 is a valid inequality'
1: every file (or directory, socket, etc) that doesn't start with a period, unless you've set a shell option (such as dotglob) to specifically enable dot-file globbing.
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
edited Dec 8 at 12:48
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
answered Dec 7 at 20:13
Jeff Schaller
38.1k1053124
38.1k1053124
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
add a comment |
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
@John, regarding your suggested edit, the wildcard/glob picks up directories and sockets and pipes, etc. -- not just "regular files"
– Jeff Schaller
Dec 8 at 12:49
add a comment |
up vote
4
down vote
There are two things happening here...
First is that the shell sees the * character and replaces it with a list of files in the current directory. This is known as "globbing"
In addition the > 5 is seen as a redirection command.
so
echo 2 * 3 > 5 is a valid inequality
Is parsed as
echo 2 * 3 is a valid inequality > 5
This results in a file called "5" being created with the contents "2 list of current files 3 is a valid inequality".
To prevent this from happening we need to use quotes
echo '2 * 3 > 5 is a valid inequality'
The '...' prevents the shell from interpreting the special characters and displays the string you entered.
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
add a comment |
up vote
4
down vote
There are two things happening here...
First is that the shell sees the * character and replaces it with a list of files in the current directory. This is known as "globbing"
In addition the > 5 is seen as a redirection command.
so
echo 2 * 3 > 5 is a valid inequality
Is parsed as
echo 2 * 3 is a valid inequality > 5
This results in a file called "5" being created with the contents "2 list of current files 3 is a valid inequality".
To prevent this from happening we need to use quotes
echo '2 * 3 > 5 is a valid inequality'
The '...' prevents the shell from interpreting the special characters and displays the string you entered.
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
add a comment |
up vote
4
down vote
up vote
4
down vote
There are two things happening here...
First is that the shell sees the * character and replaces it with a list of files in the current directory. This is known as "globbing"
In addition the > 5 is seen as a redirection command.
so
echo 2 * 3 > 5 is a valid inequality
Is parsed as
echo 2 * 3 is a valid inequality > 5
This results in a file called "5" being created with the contents "2 list of current files 3 is a valid inequality".
To prevent this from happening we need to use quotes
echo '2 * 3 > 5 is a valid inequality'
The '...' prevents the shell from interpreting the special characters and displays the string you entered.
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
There are two things happening here...
First is that the shell sees the * character and replaces it with a list of files in the current directory. This is known as "globbing"
In addition the > 5 is seen as a redirection command.
so
echo 2 * 3 > 5 is a valid inequality
Is parsed as
echo 2 * 3 is a valid inequality > 5
This results in a file called "5" being created with the contents "2 list of current files 3 is a valid inequality".
To prevent this from happening we need to use quotes
echo '2 * 3 > 5 is a valid inequality'
The '...' prevents the shell from interpreting the special characters and displays the string you entered.
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
answered Dec 7 at 20:13
Stephen Harris
24.3k24477
24.3k24477
add a comment |
add a comment |
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