优化壳一个衬里

Question

需要优化UNIX shell一行

cat ${TEMPFILE} | cut -d ' ' -f1 | sed '/^$/d'| sed '1,4d'| sed 's/$/|ON_ICE|OFF_ICE/g' > ${MYREPORT}

因为这会导致性能问题。

Answer 1

只调用一次sed：

cat ${TEMPFILE}|cut -d ' ' -f1|sed '/^$/d;1,4d;s/$/|ON_ICE|OFF_ICE/g'>${MYREPORT}

Answer 2

awk '/^$/ || ++count <= 4 {next} {print $1 "|ON_ICE|OFF_ICE"}' "$TEMPFILE" > "$MYREPORT"

Answer 3

在

cat ${TEMPFILE} | cut -d ' ' -f1 | sed '/^$/d' | sed '1,4d' | sed 's/$/|ON_ICE|OFF_ICE/g' > ${MYREPORT}

显然你可以用尾巴+4

替换sed'1,4d'

Answer 4

使用awk如下：

awk '{$0=$1};if (NF>1){++rec}; if(NF > 1 && rec > 4 ){sub(/$/,"|ON_ICE|OFF_ICE")); print};' ${TEMPFILE} > ${MYREPORT}