function

问题 Consider: true; run_backup=$? if [[ $run_backup ]]; then echo "The user wants to run the backup" fi ...and... false; run_backup=$? if [[ $run_backup ]]; then echo "The user wants to run the backup" fi The user wants to run the backup is emitted whether run_backup has 0 (success) or 1 (false)! What's going on here? (My real command, instead of true or false , is of the form zenity --question --text "..." ). 回答1: [[ $run_backup ]] is not a Boolean check; it fails only if its argument is an

问题 Consider: true; run_backup=$? if [[ $run_backup ]]; then echo "The user wants to run the backup" fi ...and... false; run_backup=$? if [[ $run_backup ]]; then echo "The user wants to run the backup" fi The user wants to run the backup is emitted whether run_backup has 0 (success) or 1 (false)! What's going on here? (My real command, instead of true or false , is of the form zenity --question --text "..." ). 回答1: [[ $run_backup ]] is not a Boolean check; it fails only if its argument is an

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 I'm learn tensorflow2.0 from official tutorials.I can understand the result from below code. def square_if_positive(x): return [i ** 2 if i > 0 else i for i in x] square_if_positive(range(-5, 5)) # result [-5, -4, -3, -2, -1, 0, 1, 4, 9, 16] But if I change the inputs with tensor not python code, just like this def square_if_positive(x): return [i ** 2 if i > 0 else i for i in x] square_if_positive(tf.range(-5, 5)) I get below error!! OperatorNotAllowedInGraphError Traceback (most recent call

问题 I am trying to make an alias that overrides the cd command. This is going to execute a script before and after the "real" cd . Here is what I have so far: alias cd="echo before; cd $1; echo after" This executes the echo before and echo after command however it always changes directory ~ How would I fix this? I also tried cd(){ echo before; cd $1; echo after; } however it repetedly echos "before". 回答1: I also tried cd(){ echo before; cd $1; echo after; } however it repetedly echos "before".

问题 I am trying to make an alias that overrides the cd command. This is going to execute a script before and after the "real" cd . Here is what I have so far: alias cd="echo before; cd $1; echo after" This executes the echo before and echo after command however it always changes directory ~ How would I fix this? I also tried cd(){ echo before; cd $1; echo after; } however it repetedly echos "before". 回答1: I also tried cd(){ echo before; cd $1; echo after; } however it repetedly echos "before".

问题 I would like to create a more specific error message for Postgres CHECK IN violations. So for example a violation of the following CHECK constraint on a column: management_zone varchar(15) NOT NULL CHECK (management_zone IN ('Marine', 'Terrestrial') ), should return a custom error message such as ie.: "Hint: Check spelling. Only allowed inputs are: 'Marine', 'Terrestrial'. The best solution I have seen so far solves it by using the error message as the name of the check constraint, ie ADD