Use of legacy backtick SH-2006
Anti-pattern
Major
a month ago
—
2 months old
Use $(...) notation instead of legacy backticks
...10if [ ! -f $numPath/num ]; then
11 echo "0" > $numPath/num
12fi
13num=`cat $numPath/num`14num=$(($num + 1))
15echo $num > $numPath/num
16Use $(...) notation instead of legacy backticks
... 55 write_log "RAW input: '`echo "${REPLY}" | tr -cd '[ -~]'`'"
56
57 COMMAND="`echo "${REPLY}" | awk '{print $1}' | tr -cd '\40-\176' | tr 'a-z' 'A-Z'`"
58 ARGS="`echo "${REPLY}" | tr -cd '\40-\176' | awk '{for(i=2;i<=NF;i++){printf "%s ", $i};printf "\n"}' | sed 's/ $//'`" 59
60 write_log "Command: \"${COMMAND}\""
61 write_log "Arguments: \"${ARGS}\""Use $(...) notation instead of legacy backticks
... 54 if [ "$REPLY" ] ; then
55 write_log "RAW input: '`echo "${REPLY}" | tr -cd '[ -~]'`'"
56
57 COMMAND="`echo "${REPLY}" | awk '{print $1}' | tr -cd '\40-\176' | tr 'a-z' 'A-Z'`" 58 ARGS="`echo "${REPLY}" | tr -cd '\40-\176' | awk '{for(i=2;i<=NF;i++){printf "%s ", $i};printf "\n"}' | sed 's/ $//'`"
59
60 write_log "Command: \"${COMMAND}\""Use $(...) notation instead of legacy backticks
... 52 TIMEOUT=30
53
54 if [ "$REPLY" ] ; then
55 write_log "RAW input: '`echo "${REPLY}" | tr -cd '[ -~]'`'" 56
57 COMMAND="`echo "${REPLY}" | awk '{print $1}' | tr -cd '\40-\176' | tr 'a-z' 'A-Z'`"
58 ARGS="`echo "${REPLY}" | tr -cd '\40-\176' | awk '{for(i=2;i<=NF;i++){printf "%s ", $i};printf "\n"}' | sed 's/ $//'`"Use $(...) notation instead of legacy backticks
... 33 echo '---' >>${LOGFILE}
34 fi
35 let LINES+=1
36 [ ${LOGGING} = 0 ] || echo -e "`date '+%b %d %H:%M'` pop3 $*" >>${LOGFILE} 37}
38
39ANSWER="+OK Fake POP3 Service Ready"
Description
Consider using the $(...) notation instead.
Backtick command substitution \...`` is legacy syntax with several issues.
* It has a series of undefined behaviors related to quoting in POSIX.
* It imposes a custom escaping mode with surprising results.
* It's exceptionally hard to nest.
$(...) command substitution has none of these problems, and is therefore strongly encouraged.
Problematic code:
echo "You are running on `uname`"
Preferred code:
echo "You are running on $(uname)"
Read more about it here:
- BashFq: Why is $(...) preferred over \...`` (backticks)?.