Add or Remove trailing slash in bash

slash.sh

### Add trailing slash if needed

STR="/i/am/a/path"

length=${#STR}
last_char=${STR:length-1:1}

[[ $last_char != "/" ]] && STR="$STR/"; :

echo "$STR" # => /i/am/a/path/


### Remove trailing slash if given

STR="/i/am/a/path/"

length=${#STR}
last_char=${STR:length-1:1}

[[ $last_char == "/" ]] && STR=${STR:0:length-1}; :

echo "$STR" # => /i/am/a/path

With Bash 4.2 this can be condensed into one-liners:

[[ "${STR}" != */ ]] && STR="${STR}/"

[[ "${STR}" == */ ]] && STR="${STR: : -1}"

another way to do it:

[[ ! $(echo ${STR} | rev |  cut -d '/' -f 1 | rev) == "" ]] && STR=${STR}/
[[ $(echo ${STR} | rev |  cut -d '/' -f 1 | rev) == "" ]] && STR=$(echo $STR | sed 's/.$//')

it is not better then you said, jsut another way

add slash

STR="${STR%/}/"

remove slash

STR="${STR%/}"

add slash

STR="${STR%/}/"

remove slash

STR="${STR%/}"

Nicely done!