I always confuse myself as to whether the correct flags for java and the jshell are -cp or --classpath or --class-path or something else, so instead of trying to remember something like a normal human, I instead spent a few hours pulling this script together.
It automatically detects any variation of cp, classpath, and class-path flags in a series of command-line arguments, and concatenates all of the correct arguments to give you a nice, clean classpath. I hope it's useful!
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| #!/usr/bin/env bash | |
| #------------------------------------------------------------------------------- | |
| # | |
| # array_contains - returns 0 if array contains the specified value, else 1 | |
| # | |
| # $1 : term to search for | |
| # $2+ : array to inspect | |
| # | |
| # sources: | |
| # https://stackoverflow.com/a/8574392/2925434 | |
| # | |
| #------------------------------------------------------------------------------- | |
| function array_contains { | |
| local match="$1" | |
| shift | |
| for arg; do | |
| [[ "$match" == "$arg" ]] && return 0 | |
| done | |
| return 1 | |
| } | |
| # usage: | |
| # | |
| # $ if $(array_contains 4 5 7 8); then echo "contains"; else echo "doesn't"; fi | |
| # doesn't | |
| # | |
| # $ if $(array_contains 4 4 5 7 8); then echo "contains"; else echo "doesn't"; fi | |
| # contains | |
| # usage: | |
| # | |
| # $ test[0]=a; test[1]=b; test[2]=c; echo ${test[1]} | |
| # b | |
| # | |
| # $ if $(array_contains c "${test[@]}"); then echo "contains"; else echo "doesn't"; fi | |
| # contains | |
| # | |
| # $ if $(array_contains d "${test[@]}"); then echo "contains"; else echo "doesn't"; fi | |
| # doesn't |
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| #!/usr/bin/env bash | |
| #------------------------------------------------------------------------------- | |
| # | |
| # is_flag - infer whether or not a command-line argument is a flag OR empty | |
| # | |
| # returns 0: arg is flag | |
| # returns 1: arg is not a flag, not empty | |
| # returns 2: arg is empty | |
| # | |
| # sources: | |
| # https://stackoverflow.com/a/10218528/2925434 | |
| # https://stackoverflow.com/a/17287097/2925434 | |
| # | |
| #------------------------------------------------------------------------------- | |
| function is_flag { | |
| local arg="" | |
| local retval=1 | |
| # if is empty, not a flag | |
| if [[ -z "$1" ]]; then | |
| arg="\"\"" | |
| retval=2 | |
| else | |
| # get first and last characters | |
| local firstchar="${1:0:1}" | |
| local lastchar="${1: -1}" | |
| local short="$1" | |
| # if surrounded by quotes, remove them | |
| if [[ $firstchar == "\"" && $lastchar == "\"" ]] || | |
| [[ $firstchar == "'" && $lastchar == "'" ]]; then | |
| local lenm2=$((${#1}-2)) | |
| short="${1:1:$lenm2}" | |
| fi | |
| # if is empty, not a flag | |
| if [[ -z "$short" ]]; then | |
| arg="\"\"\"\"" | |
| retval=2 | |
| # if contains spaces, not a flag -- surround with quotes | |
| elif [[ "$short" = *[[:space:]]* ]]; then | |
| arg="\"$short\"" | |
| # else, if starts with "-", is a flag -- no quotes | |
| elif [[ "${short:0:1}" == "-" ]]; then | |
| arg="$short" | |
| retval=0 | |
| # else, isn't a flag -- surround with quotes | |
| else | |
| arg="\"$short\"" | |
| fi | |
| fi | |
| # print arg and return | |
| echo "${arg}" | |
| return $retval | |
| } | |
| # usage: | |
| # | |
| # $ is_flag p # not a flag, surrounded in quotes | |
| # "p" | |
| # | |
| # $ is_flag -p # is a flag, not surrounded in quotes | |
| # -p | |
| # | |
| # $ is_flag "-p" # is a flag, even though surrounded by quotes | |
| # -p | |
| # | |
| # $ is_flag --p # is a flag, any number of - allowed | |
| # --p | |
| # | |
| # $ is_flag "-p a" # not a flag, because quoted and contains spaces | |
| # "-p a" | |
| # | |
| # $ is_flag "-pa" # is a flag, because contains no spaces | |
| # -pa | |
| # | |
| # $ is_flag # no argument given, return empty string | |
| # "" | |
| # | |
| # $ is_flag "" # empty string given, return empty string | |
| # "" | |
| # | |
| # $ is_flag "\"\"" # empty quoted string, return same | |
| # """" |
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| #!/usr/bin/env bash | |
| export JARS_HOME=~/.jenv/jars | |
| # jar locations | |
| export JAVA_JARS_HOME=$JARS_HOME/java | |
| export SCALA_JARS_HOME=$JARS_HOME/scala | |
| # jar lists | |
| export JAVA_JARS_LIST=".:$JAVA_JARS_HOME/\*" | |
| export SCALA_JARS_LIST=".:$JAVA_JARS_HOME/\*:$SCALA_JARS_HOME/\*" | |
| # overrides for jshell, java, etc. | |
| function jshell { | |
| merge_classpath -cp $(eval "echo $JAVA_JARS_LIST") $@ | xargs -o $(whereis jshell) | |
| } | |
| function scala { # replace --class-path with -cp for Scala only | |
| merge_classpath -cp $(eval "echo $SCALA_JARS_LIST") $@ | \ | |
| sed 's/--class-path/-cp/' | xargs -o $SCALA_HOME/bin/scala | |
| } | |
| function java { | |
| merge_classpath -cp $(eval "echo $JAVA_JARS_LIST") $@ | xargs -o $JAVA_HOME/bin/java | |
| } | |
| function derby { | |
| java org.apache.derby.tools.ij | |
| } |
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| #!/usr/bin/env bash | |
| #------------------------------------------------------------------------------- | |
| # | |
| # merge_classpath - merge '-cp' '-classpath' and '--class-path' flags and args | |
| # | |
| # sources: | |
| # https://stackoverflow.com/a/1498876/2925434 | |
| # https://stackoverflow.com/a/18568726/2925434 | |
| # https://stackoverflow.com/a/171041/2925434 | |
| # https://stackoverflow.com/a/1405641/2925434 | |
| # https://stackoverflow.com/a/17573592/2925434 | |
| # | |
| #------------------------------------------------------------------------------- | |
| function merge_classpath { | |
| # loop over all arguments and find any '-cp', etc. flags | |
| flags[0]="-cp" | |
| flags[1]="-classpath" | |
| flags[2]="-class-path" | |
| flags[3]="--cp" | |
| flags[4]="--classpath" | |
| flags[5]="--class-path" | |
| # any argument which immediately follows one of these flags is assumed to be | |
| # another jar file (or list of jar files) to be added to the classpath | |
| # UNLESS the next argument is ALSO a flag (or an empty string) in which case, | |
| # the first ('-cp') flag is ignored | |
| # all other flags and their relationships to each other are kept intact, | |
| # quotes are put around every non-flag argument | |
| local classpath="" | |
| local otherargs="" | |
| for ((ii=1; ii<=$#; ++ii)); do | |
| local jj=$((ii+1)) | |
| local this="${!ii}" # current flag / argument | |
| local next="${!jj}" # next flag / argument | |
| # if THIS arg is a -cp-like flag | |
| if array_contains "${this}" "${flags[@]}"; then | |
| # check if the next arg is a flag or empty | |
| is_flag "\"${next}\"" > /dev/null 2>&1 | |
| # AND IF the NEXT arg is NOT empty AND NOT a flag, then | |
| if [ $? -eq 1 ]; then | |
| # add to classpath: | |
| # first element added to classpath? | |
| if [[ "$classpath" == "" ]]; then | |
| classpath+="${!jj}" | |
| # prepend all following ones with a ":" | |
| else | |
| classpath+=":${!jj}" | |
| fi | |
| # increment ii to skip next element | |
| ((ii++)) | |
| # if the next arg is invalid or missing, ignore this -cp-like flag | |
| fi | |
| # if this is some other flag / argument, keep intact | |
| else | |
| otherargs+=" $(is_flag \""${this}"\")" | |
| fi | |
| done | |
| # if classpath is empty, return an error code | |
| if [[ -z "$classpath" ]]; then | |
| echo "${otherargs#?}" # strip leading ' ' | |
| return 1 | |
| fi | |
| # else, send classpath and other flags and args to stdout and return normally | |
| echo "--class-path \"$classpath\"$otherargs" | |
| return 0 | |
| } | |
| # usage: | |
| # | |
| # $ merge_classpath -cp . --class-path /path/to/jars -classpath "some:more:jars" | |
| # --class-path ".:/path/to/jars:some:more:jars" | |
| # | |
| # $ merge_classpath -cp -cp /handles/bad/args --classpath /and/forgotten/ones -cp | |
| # --class-path "/handles/bad/args:/and/forgotten/ones" | |
| # | |
| # $ merge_classpath -cp "retains : spaces" --classpath "in quoted args" | |
| # --class-path "retains : spaces:in quoted args" | |
| # | |
| # $ merge_classpath -f "no classpath flags" "so no --class-path added" | |
| # -f "no classpath flags" "so no --class-path added" | |
| # | |
| # $ merge_classpath "-quoted" "flags have quotes removed" | |
| # -quoted "flags have quotes removed" |
Top comments (2)
An alternative to the for loop is the while loop with the shift command. It is without indexes and much simpler.
BTW: This script look like in Java. Bash is not Java, Bash is different. Use echo for return values from function.
Hi Vlastimil. I used indices because I need the i-th argument and also the i+1-th argument at the same time.
shiftthrows away earlier arguments. There might be a way to refactor it, which I would love to see.I use exit codes to indicate the status of the method -- i.e.
0if everything went fine,1if there was an error, etc. I also useechoto print strings meant to be "returned" from the functions. See above!