There are spaces in the for loop variable in the shell -- IFS variable

• In the use of shell Of for loop , If there is a space in the middle of the string of the loop , Then the loop will be automatically divided , Here's the solution

 Just change  shell The separator is just 
 stay for Modify before loop IFS Variable , Example ：
OLDIFS="$IFS"  # Back up old IFS Variable 
IFS=$'\n'   # Change the separator to newline 

for i in `cat aaa`  #aaa The public key is stored in the file 
do
echo "$i"
done
IFS="$OLDIFS"  # Restore IFS Variable 

• notes ：

IFS Information about variables ：

1. Shell Put variables IFS Every character in is treated as a Separator (delimeter), Use these characters as the terminator of each field for segmentation .
2. If IFS No settings , perhaps IFS The value of is set to "\t\n"(space, tab and newline), Then all the at the beginning and end of the operation object space, tab and newline Sequences will be ignored , But in the middle of the operation object space, tab and newline The sequence will work as a delimiter .
3. If IFS It's not worth it The default value is ( For example, in the program IFS It has been set ), Only in IFS White space characters in ( May be space, tab or newline One or more of ) Will be ignored at the beginning and end of the word , Here are words , Instead of the entire operation object .
4. IFS When more than one non white space character in the appears consecutively , Each non white space character is treated as a separate separator , But multiple consecutive white space characters are treated as a separator .
5. If IFS It's empty (“null”), Word segmentation is not performed .