Shell script-Judging Type

Test-judged

See below:

1 Echo " exist " Echo " Not exist "

Determine if/opt/a.txt exists, output exist, otherwise output not exist

Test also has many uses:

2. A "file type" judgment about a file name, such as TEST-E filename indicates whether or not it exists
   1. -e Whether the file name exists
   2. -f The file name exists and is a file
   3. -D whether the file name exists and is a directory
4. Permissions on the file, such as Test-f fileName, to determine whether the file is readable
   1. -R
   2. -W
   3. -X
6. For a comparison between two files, such as Test file1-nt file2
   1. -nt (newer than) to determine whether File1 is newer than file2
   2. -ot (older than) to determine whether File1 is older than file2
8. About the judgments between two integers, such as test n1-eq N2
   1. -eq judgment equals
   2. -ne judgment is not equal
   3. -GT N1 greater than N2
   4. -lt N1 less than N2
   5. -ge greater than or equal to
   6. -le less than or equal to
10. About string Comparisons
    1. Test-z String If string is an empty string, returns True
    2. Test-n String If string is an empty string, returns false
    3. Test STR1=STR2
    4. Test STR1!=STR2
12. Multiple Criteria Determination
    1. -A two conditions are also established, such as Test-e file1-a-e file2, to determine whether File1 and file2 are present
    2. -O Any condition that is set up, such as Test-e File1-o-e file2,file1 or file2 any one presence returns True
    3. ! Negative, like test! -e File1, indicating that FILE1 does not exist returns true

[  ... ] Judging type

Often used in the judgment of IF statements

Note: Each component in [] must be separated by a space character; the variables are best enclosed in double quotation marks; constants are enclosed in double quotes

Shell script-Judging Type