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0

when I type

$ cd `

into a terminal, then I get this

>

even ls or cd is not working, please explain the meaning of the above command and how do I exit it?

command-line bash cd-command

share|improve this question

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Ctrl+C or another `. All quotes must be terminated properly. See en.wikipedia.org/wiki/Command_substitution
  
  – FedonKadifeli
  May 6 at 20:25
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  As for the meaning, the single backquote, ` , tells the shell that you are starting a command substitution and > means that the shell wants you to complete it.
  
  – John1024
  May 6 at 20:28
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Duplicate on Unix & Linux: What is the effect of a lone backtick at the end of a command line?, related: What mode does the terminal go into when I type a single quote?, Terminal shows > after entering backslash
  
  – wjandrea
  May 6 at 21:08
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Possible duplicate of Unable to enter new commands in terminal — stuck with “>”
  
  – wjandrea
  May 6 at 21:10
  

  
  
  
  

add a comment | 

0

when I type

$ cd `

into a terminal, then I get this

>

even ls or cd is not working, please explain the meaning of the above command and how do I exit it?

command-line bash cd-command

share|improve this question

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Ctrl+C or another `. All quotes must be terminated properly. See en.wikipedia.org/wiki/Command_substitution
  
  – FedonKadifeli
  May 6 at 20:25
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  As for the meaning, the single backquote, ` , tells the shell that you are starting a command substitution and > means that the shell wants you to complete it.
  
  – John1024
  May 6 at 20:28
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Duplicate on Unix & Linux: What is the effect of a lone backtick at the end of a command line?, related: What mode does the terminal go into when I type a single quote?, Terminal shows > after entering backslash
  
  – wjandrea
  May 6 at 21:08
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Possible duplicate of Unable to enter new commands in terminal — stuck with “>”
  
  – wjandrea
  May 6 at 21:10
  

  
  
  
  

add a comment | 

when I type

$ cd `

into a terminal, then I get this

>

even ls or cd is not working, please explain the meaning of the above command and how do I exit it?

command-line bash cd-command

share|improve this question

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$ cd `

>

share|improve this question

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited May 7 at 2:36

pomsky

34.4k11108141

edited May 7 at 2:36

pomsky

34.4k11108141

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

New contributor

Vaishnava Hari is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked May 6 at 20:22

Vaishnava HariVaishnava Hari

62

2 Answers
2

active

oldest

votes

8

Backticks work in pairs. Bash is waiting for you to provide another backtick to complete the command/expression.

> is simply a prompt for newline which is determined by the value of PS2 generally defined in .bashrc.

Whenever you hit Enter (if the command/expression is incomplete, i.e. backtick isn't closed), bash expects you to complete the command/expression either in one line or multiple lines. For example, you want to evaluate value of 'a' using expr. You can do

$ a=`
> expr 1 + 3`

will be interpreted as

$ a=`expr 1 + 3`

So, if you want to run some command either complete the required expression or if there is no command/expression required in between backticks, refrain from using that. Another way is to use Ctrl+C, but that would be a Keyboard Interrupt and will make your command to terminate immediately.

To read more about backticks, read these questions on U&L: Understanding backtick and What does ` (backquote/backtick) mean in commands?

share|improve this answer

edited May 6 at 21:19

answered May 6 at 20:29

KulfyKulfy

5,85372248

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is a good answer but a=`echo $b` is in most cases a bad example. You will get the value of $b, with all sequences of whitespace replaced with single spaces, then each word will be expanded as a glob based on the files of the current directory, and then all trailing newlines will be trimmed, and a single newline will be added in the end. I'd say that 99.9% of the time you'd want a=$b, and the rest a=$(echo "$b") if you want a single trailing newline.
  
  – user000001
  May 6 at 20:59
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hey @user000001, thank you for your valuable comment. What about a=`expr 1 + 3` example? (Formatting in comments sucks!!!)
  
  – Kulfy
  May 6 at 21:04
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Yes, that's much better, though surely someone will come along and complain that since the question is tagged [bash], you'd be using a=$((b+3)) in real code instead of expr ;)
  
  – user000001
  May 6 at 21:09
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @user000001 Replaced. The question is about ``` ` ``` and >, I don't think such complain would occur ;-).
  
  – Kulfy
  May 6 at 21:20
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Consider the complaint made -- we've got so many people using 1970s-era expr syntax because they're used to seeing it around so they think it's normal/expected/correct, vs standardized-since-the-1990s (and thus not at all a bashism) $(( ... )) POSIX math syntax. date is a lot more defensible as an example, since it's legitimately needed when writing code for POSIX shells (or versions of bash that aren't recent 4.x adding printf '%(...)T') today.
  
  – Charles Duffy
  May 6 at 21:57
  
  

  
  
  
  

add a comment | 

5

The backticks create an execution environment called command substitution. It is used like this, for example:

echo "The date today is `date`"

Here, the date command is executed first, and its output replaces the part between the backticks, so in the end you get a string with the current date.

Command substitution may span multiple lines, so when you type:

cd `

and press Enter, bash expects you to complete the command substitution, before executing the cd command. This can be broken either by closing the backtick and pressing Enter, or by pressing CTRL-c (This will abort the command without anything getting executed).

Note that modern guidelines prefer to avoid the backtick syntax for command substitution, and to use $( ) instead, so the first example would be:

echo "The date today is $(date)"

share|improve this answer

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

add a comment | 

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8

Backticks work in pairs. Bash is waiting for you to provide another backtick to complete the command/expression.

> is simply a prompt for newline which is determined by the value of PS2 generally defined in .bashrc.

Whenever you hit Enter (if the command/expression is incomplete, i.e. backtick isn't closed), bash expects you to complete the command/expression either in one line or multiple lines. For example, you want to evaluate value of 'a' using expr. You can do

$ a=`
> expr 1 + 3`

will be interpreted as

$ a=`expr 1 + 3`

So, if you want to run some command either complete the required expression or if there is no command/expression required in between backticks, refrain from using that. Another way is to use Ctrl+C, but that would be a Keyboard Interrupt and will make your command to terminate immediately.

To read more about backticks, read these questions on U&L: Understanding backtick and What does ` (backquote/backtick) mean in commands?

share|improve this answer

edited May 6 at 21:19

answered May 6 at 20:29

KulfyKulfy

5,85372248

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is a good answer but a=`echo $b` is in most cases a bad example. You will get the value of $b, with all sequences of whitespace replaced with single spaces, then each word will be expanded as a glob based on the files of the current directory, and then all trailing newlines will be trimmed, and a single newline will be added in the end. I'd say that 99.9% of the time you'd want a=$b, and the rest a=$(echo "$b") if you want a single trailing newline.
  
  – user000001
  May 6 at 20:59
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hey @user000001, thank you for your valuable comment. What about a=`expr 1 + 3` example? (Formatting in comments sucks!!!)
  
  – Kulfy
  May 6 at 21:04
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Yes, that's much better, though surely someone will come along and complain that since the question is tagged [bash], you'd be using a=$((b+3)) in real code instead of expr ;)
  
  – user000001
  May 6 at 21:09
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @user000001 Replaced. The question is about ``` ` ``` and >, I don't think such complain would occur ;-).
  
  – Kulfy
  May 6 at 21:20
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Consider the complaint made -- we've got so many people using 1970s-era expr syntax because they're used to seeing it around so they think it's normal/expected/correct, vs standardized-since-the-1990s (and thus not at all a bashism) $(( ... )) POSIX math syntax. date is a lot more defensible as an example, since it's legitimately needed when writing code for POSIX shells (or versions of bash that aren't recent 4.x adding printf '%(...)T') today.
  
  – Charles Duffy
  May 6 at 21:57
  
  

  
  
  
  

add a comment | 

8

Backticks work in pairs. Bash is waiting for you to provide another backtick to complete the command/expression.

> is simply a prompt for newline which is determined by the value of PS2 generally defined in .bashrc.

Whenever you hit Enter (if the command/expression is incomplete, i.e. backtick isn't closed), bash expects you to complete the command/expression either in one line or multiple lines. For example, you want to evaluate value of 'a' using expr. You can do

$ a=`
> expr 1 + 3`

will be interpreted as

$ a=`expr 1 + 3`

So, if you want to run some command either complete the required expression or if there is no command/expression required in between backticks, refrain from using that. Another way is to use Ctrl+C, but that would be a Keyboard Interrupt and will make your command to terminate immediately.

To read more about backticks, read these questions on U&L: Understanding backtick and What does ` (backquote/backtick) mean in commands?

share|improve this answer

edited May 6 at 21:19

answered May 6 at 20:29

KulfyKulfy

5,85372248

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This is a good answer but a=`echo $b` is in most cases a bad example. You will get the value of $b, with all sequences of whitespace replaced with single spaces, then each word will be expanded as a glob based on the files of the current directory, and then all trailing newlines will be trimmed, and a single newline will be added in the end. I'd say that 99.9% of the time you'd want a=$b, and the rest a=$(echo "$b") if you want a single trailing newline.
  
  – user000001
  May 6 at 20:59
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hey @user000001, thank you for your valuable comment. What about a=`expr 1 + 3` example? (Formatting in comments sucks!!!)
  
  – Kulfy
  May 6 at 21:04
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Yes, that's much better, though surely someone will come along and complain that since the question is tagged [bash], you'd be using a=$((b+3)) in real code instead of expr ;)
  
  – user000001
  May 6 at 21:09
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @user000001 Replaced. The question is about ``` ` ``` and >, I don't think such complain would occur ;-).
  
  – Kulfy
  May 6 at 21:20
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Consider the complaint made -- we've got so many people using 1970s-era expr syntax because they're used to seeing it around so they think it's normal/expected/correct, vs standardized-since-the-1990s (and thus not at all a bashism) $(( ... )) POSIX math syntax. date is a lot more defensible as an example, since it's legitimately needed when writing code for POSIX shells (or versions of bash that aren't recent 4.x adding printf '%(...)T') today.
  
  – Charles Duffy
  May 6 at 21:57
  
  

  
  
  
  

add a comment | 

Backticks work in pairs. Bash is waiting for you to provide another backtick to complete the command/expression.

> is simply a prompt for newline which is determined by the value of PS2 generally defined in .bashrc.

Whenever you hit Enter (if the command/expression is incomplete, i.e. backtick isn't closed), bash expects you to complete the command/expression either in one line or multiple lines. For example, you want to evaluate value of 'a' using expr. You can do

$ a=`
> expr 1 + 3`

will be interpreted as

$ a=`expr 1 + 3`

So, if you want to run some command either complete the required expression or if there is no command/expression required in between backticks, refrain from using that. Another way is to use Ctrl+C, but that would be a Keyboard Interrupt and will make your command to terminate immediately.

To read more about backticks, read these questions on U&L: Understanding backtick and What does ` (backquote/backtick) mean in commands?

share|improve this answer

edited May 6 at 21:19

answered May 6 at 20:29

KulfyKulfy

5,85372248

$ a=`
> expr 1 + 3`

$ a=`expr 1 + 3`

share|improve this answer

edited May 6 at 21:19

answered May 6 at 20:29

KulfyKulfy

5,85372248

answered May 6 at 20:29

KulfyKulfy

5,85372248

answered May 6 at 20:29

KulfyKulfy

5,85372248

5

The backticks create an execution environment called command substitution. It is used like this, for example:

echo "The date today is `date`"

Here, the date command is executed first, and its output replaces the part between the backticks, so in the end you get a string with the current date.

Command substitution may span multiple lines, so when you type:

cd `

and press Enter, bash expects you to complete the command substitution, before executing the cd command. This can be broken either by closing the backtick and pressing Enter, or by pressing CTRL-c (This will abort the command without anything getting executed).

Note that modern guidelines prefer to avoid the backtick syntax for command substitution, and to use $( ) instead, so the first example would be:

echo "The date today is $(date)"

share|improve this answer

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

add a comment | 

5

The backticks create an execution environment called command substitution. It is used like this, for example:

echo "The date today is `date`"

Here, the date command is executed first, and its output replaces the part between the backticks, so in the end you get a string with the current date.

Command substitution may span multiple lines, so when you type:

cd `

and press Enter, bash expects you to complete the command substitution, before executing the cd command. This can be broken either by closing the backtick and pressing Enter, or by pressing CTRL-c (This will abort the command without anything getting executed).

Note that modern guidelines prefer to avoid the backtick syntax for command substitution, and to use $( ) instead, so the first example would be:

echo "The date today is $(date)"

share|improve this answer

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

add a comment | 

The backticks create an execution environment called command substitution. It is used like this, for example:

echo "The date today is `date`"

Here, the date command is executed first, and its output replaces the part between the backticks, so in the end you get a string with the current date.

Command substitution may span multiple lines, so when you type:

cd `

and press Enter, bash expects you to complete the command substitution, before executing the cd command. This can be broken either by closing the backtick and pressing Enter, or by pressing CTRL-c (This will abort the command without anything getting executed).

Note that modern guidelines prefer to avoid the backtick syntax for command substitution, and to use $( ) instead, so the first example would be:

echo "The date today is $(date)"

share|improve this answer

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

echo "The date today is `date`"

cd `

echo "The date today is $(date)"

share|improve this answer

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

edited May 7 at 1:37

Kevin Bowen

15k155972

edited May 7 at 1:37

Kevin Bowen

15k155972

answered May 6 at 20:31

user000001user000001

5231413

answered May 6 at 20:31

user000001user000001

5231413