How to test strings for less than or equal?

2018-06-05 12:24:12

In Bash, is there a simple way to test if one string is lexicographically less than or equal to another?

I know you can do:

if [[ "a" < "b" ]]

for testing strict inequality, or

if [[ 1 -le 1 ]]

for numbers. But -le doesn't seem to work with strings, and using <= gives a syntax error.

只是否定了大于测试：

if [[ ! "a" > "b" ]]

You need to use || with an additional condition instead of <= :

[[ "$a" < "$b" || "$a" == "$b" ]]

You can flip the comparison and sign around and test negatively:

$ a="abc"
$ b="abc"
$ if ! [[ "$b" > "$a" ]] ; then  echo "a <= b" ; fi
a <= b

If you want collating sequence of "A" then "a" then "B"... use:

shopt -s nocaseglob

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