Bash - Compare variable to string "0"

Question

The "sync-mongo" file can either contain a git commit id, or 0. When the file contains 0, the if statement still isn't entered.

COMMITID=`docker exec -it ${NAME} bash -c 'cd /usr/src/app/_api; cat sync-mongo.commit'`

if [ "${COMMITID}" == "0" ]
then
  ./_configuremongo.sh -i $INPUT -o $OUTPUT -r
fi

I've also tried:

if [ ${COMMITID} -eq 0 ]
then
  ./_configuremongo.sh -i $INPUT -o $OUTPUT -r
fi

which returns : integer expression expected[: 0

daniu https://stackoverflow.com/questions/20449543/bash-equality-operators-eq -eq is for numeric comparisons Barmar 0 — WilliamNHarvey, Nov 06 '17 at 20:01
@Asthmatic How can it display only `0`? What happened to the pipes? — Barmar, Nov 06 '17 at 20:55

score 0 · Accepted Answer · answered Nov 06 '17 at 20:03

0

Maybe you have a cd alias that sends an escape sequence, and that's included in the output to $COMMITID. Try just using an absolute pathname:

COMMITID=`docker exec -it ${NAME} bash -c 'cat /usr/src/app/_api/sync-mongo.commit'`

answered Nov 06 '17 at 20:03

Barmar

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I think you're right, but abs path didnt fix it. Diff between variable and "0": 1c1 < 0 --- > 0; echo ${COMMITID#0} outputs a blank line (same as just echo) – WilliamNHarvey Nov 06 '17 at 20:48
Soln was stripping non alphanumeric chars: if [ "${COMMITID//[![:alnum:]]}" == "0" ] – WilliamNHarvey Nov 06 '17 at 20:55

Bash - Compare variable to string "0"

1 Answers1