Bash如何过滤输入文件

Question

我有一个很大的文件，里面有很多不必要的东西，需要过滤掉。所以让我感兴趣的事情是这样的：

 iteration # 20     ecut=    36.00 Ry     beta=0.10
 Davidson diagonalization with overlap
 ethr =  4.07E-13,  avg # of iterations =  3.8

 total cpu time spent up to now is   351441.3 secs

 End of self-consistent calculation

 Number of k-points >= 100: set verbosity='high' to print the bands.

 highest occupied, lowest unoccupied level (ev):     2.2896    4.1062

好的，所以我需要计算: Bg=ELUMO−EHOMO，而ELUMO和EHOMO是最高和最低的占用率。问题是我想要这样的输出：

Iteration #<number>
Bg=xxx

我的两个问题: 1.我可以通过“最高”字符串进行grep，所以我得到的每一行都是这样的：

 highest occupied, lowest unoccupied level (ev):     2.3005    4.0791

但是如何将变量设置为最高和最低的空闲级别呢？

2.由于并非每次迭代都会给出未占用级别的值(我想跳过它)，我应该如何grep/find才能始终拥有迭代编号和未占用级别？

Answer 1

使用awk

awk '/^iteration|highest/{if ($0 ~ "iteration") gsub(/ecut.*/ , "", $0); if ($0 ~ "highest") $0=($(NF-1)-$NF); print}' 

演示：

$cat file.txt 
iteration # 20     ecut=    36.00 Ry     beta=0.10
 Davidson diagonalization with overlap
 ethr =  4.07E-13,  avg # of iterations =  3.8

 total cpu time spent up to now is   351441.3 secs

 End of self-consistent calculation

 Number of k-points >= 100: set verbosity='high' to print the bands.

 highest occupied, lowest unoccupied level (ev):     2.2896    4.1062
$awk '/^iteration|highest/{if ($0~"iteration") gsub(/ecut.*/,"",$0); if ($0 ~ "highest") $0=($(NF-1)-$NF); print}'  < file.txt 
iteration # 20     
-1.8166
$

解释：

/^iteration|highest/ -- Select only rows starting with iteration or with highesh 
($0 ~ "iteration")  -- $0 means entire row, Check if row have iteration pattern
 gsub(/ecut.*/ , "", $0) -- Delete all char after **ecut**
NF -- > number of fields in row 
$NF --> last field 
$(NF-1) --> second last field 
 $0=($(NF-1)-$NF -- Set current row as second last field -  last field