linux 特定字符串次数

写入字符串

cat > test.txt << EOF
ewetrte
fsdfgf
dfghghj
dsffgd
hgfdwe
EOF

vim 查找

:%s/df/&/gn

使用grep

grep -o "df" test.txt | wc -l

awk

#### 方法1 
awk -F "df" '{print NF-1}' test.txt  | awk '{sum += $0} END {print sum}'

### 方法 2
awk -v RS="\n" '{print gsub(/e/,"&")}' a.txt |  awk '{sum += $0} END {print sum}'

### 方法3
awk '{ sum += gsub(/df/,"&")} END {print sum}' test.txt

### 方法4  $j 是shell 变量
awk -v RS="@#$j" '{print gsub(/df/,"&")}' test.txt