how to replace a variable in shell script string
bash, shell
Solution
You are missing the end of that single-quote pair in your script.
Change from:
echo $SQL | sed -e "s/'$BATCH_END/$BATCH_END/g"
To:
echo $SQL | sed -e "s/\$BATCH_END/$BATCH_END/g"
Updated - as per followup comment:
To save the result of the above replacement back into `$SQL`, do either of the following:
# Preferred way
SQL=$(echo $SQL | sed -e "s/\$BATCH_END/$BATCH_END/g")
# Old way
SQL=`echo $SQL | sed -e "s/\$BATCH_END/$BATCH_END/g"`
This is called command substitution. Either syntax (`$(...)` vs. enclosure by backticks) works, but the preferred one allows you to do nesting.
The preferred-preferred way: Herestring
This is probably a bit more advanced than what you care about, but doing it in the following way will save you a subprocess from having to use `echo` unnecessarily:
SQL=$(sed -e "s/\$BATCH_END/$BATCH_END/g" <<< $SQL)
Problem
I'm having problems getting this to work... I have a variable that is holding a SQL to with a placeholder: ``` echo $SQL SELECT PX_PROMOTION_ID, PRIORITY, STATUS, EXCLSVE, TYPE, PERORDLMT, PERSHOPPERLMT, TOTALLMT, RSV_INT, PX_GROUP_ID, CAMPAIGN_ID, STOREENT_ID, VERSION, REVISION, EFFECTIVE, TRANSFER, CDREQUIRED, EXPIRE, LASTUPDATEBY, TO_CHAR(LASTUPDATE, 'YYYYMMDD HH24MMSS') AS LASTUPDATE, TO_CHAR(STARTDATE, 'YYYYMMDD HH24MMSS') AS STARTDATE, TO_CHAR(ENDDATE, 'YYYYMMDD HH24MMSS') AS ENDDATE, TO_CHAR(RSV_TIME, 'YYYYMMDD HH24MMSS') AS RSV_TIME, RSV_REAL, TGTSALES, NAME, CODE, RSV_VCH, OPTCOUNTER FROM PX_PROMOTION WHERE LASTUPDATE BETWEEN (SELECT MAX(BATCHSTART) FROM XRPTEBATCHCONTROL) AND TIMESTAMP('$BATCH_END') ``` I have another variable that holds the value: ``` echo $BATCH_END 2012-11-14 17:06:13 ``` I want to replace the placeholder with the value. I'm not particularly great at Unix scripting, but I've tried this: ``` echo $SQL | sed -e "s/'$BATCH_END/$BATCH_END/g" ``` but it still doesn't get replaced... Can anyone help? I want to replace the placeholder, and keep the final string assigned to $SQL I also need to know how to get the value of the output back into the variable, for example, I tried: ``` SQL=`echo "$SQL" | echo "${SQL//\$BATCH_END/$BATCH_END}"` ```