Bash脚本比较if语句中的字符串和变量

Question

I am trying to get a variable to compare to a string, and then do something if it does and go on to the next, but when i look at it in debug mode, the variable just shows up as '' with nothing in it.

#!/bin/bash
echo -e "Enter the name of the document you wish to edit:\c"
read dname
CTYPE= file "$dname" | cut -d\  -f2
echo $CTYPE
VAR="ASCII"
VAR2="cannot"
if [ "$CTYPE" == "$VAR" ]
then
    vi $dname                       
fi

I get this result:

+ VAR=ASCII
+ VAR2=cannot
+ '[' '' == ASCII ']'

Where the '' is empty even though I echo d it and see that it is not empty.

I have tried it like these other ways as well, and get the same or similar non working result:

CTYPE= file "$dname" | cut -d\  -f2
if [ "$CTYPE" == "$VAR" ]

ctype= file "$dname" | cut -d\  -f2
if [ $ctype = "ASCII" ]

ctype= file "$dname" | cut -d\  -f2
if [ "$ctype" = "ASCII" ]   

ctype= file "$dname" | cut -d\  -f2
if [ "$ctype" == "ASCII" ]

Not sure what I am missing, I've read so many posts I don't know where to go from here. Thank you!

Answer 1

You have an error with CTYPE:

CTYPE=$(file "$dname" | cut -d\  -f2)

You cannot have any spaces between the = and the assignment. Further, you want the return from file "$dname" | cut -d\\ -f2 file "$dname" | cut -d\\ -f2 so you will have to enclose it in $() or with backticks.

Answer 2

When you run this command:

d= date

bash does this: set an environment variable d (with the value the empty string) only for the duration of the date command. This is densely documented here .

As David tells you, to capture the outut of a command, you need

d=$(date)