[ -f FILE ] : 如果FILE存在且是一个普通文件则为真 [ -z STRING ] : 如果STRING的长度为零则为真 [ -n STRING ] : 如果STRING的长度非零则为真 [ STRING1 = STRING2 ] : 如果两个字符串相同则为真 [ STRING1 != STRING2 ] : 如果字符串不相同则为真 1. 2. 3. 4. 5. 6. 带与或非...
grep -A2 "mach" a_file 输出 machine boots bungie 正则表达式 在使用正则表达式的场景下,推荐使用egrep(grep -E) egrep, fgrep 和 grep 不同之处 首先: egrep 等价 grep -E fgrep 等价 grep -F 现有文本: grep searches for any string in list of strings or flie. It is very fast. (f|g)ile ...
print array[a] //字符串数组下标只能用这种方式遍历 1 awk'BEGIN{array["var1"]="Jin";array["var2"]="Hao";array["var3"]="Fang";for(a in array) print array[a]}'
PATTERNS is one or more patterns separated by newline characters, and grep prints each line that matches a pattern. Typically PATTERNS should be quoted when grep is used in a shell command. A FILE of “-” stands for standard input. If no FILE is given, recursive searches examine the ...
In December 2003, the Oxford English Dictionary Online added draft entries for "grep" as both a noun and a verb. LASER-wikipedia2 比如,如果我们想利用 grep 在文件中查找 字符串-k,那么我们可以写成 grep -- -k myfile。 For example, if we want to use grep to search for the string –...
We then introduce the command grep , that searches for a string, and the command tr that transposes characters, with a view to extending our knowledge of the metacharacters. Y Nishinuma,R Espesser - Macmillan Education UK 被引量: 0发表: 1987年 Introduction to String Matching and Modification...
array[i]=a 数组长度: ${#array[@]} 删除: unset array[i] 删除整个数组: unset array 数值变量;local变量声明 shell里默认使用全局变量,局部变量使用local 声明;尤其函数中:嵌套调用注意;函数中用local声明;否则会用到上层调用函数的变量。 for i到n ...
--A num``--after-context=num:打印匹配行后的上下文行中的 num 行。 --B num``--before-context=num:打印匹配行前的上下文行中的 num 行。 --C num``-num``--context=num:打印匹配行前和匹配行后的上下文行中的 num 行。 ---group-separator=string:当使用-A、-B、-C选项时,在每组行之间打印...
Search for a string in a stream of text Another common way to usegrepis with apipe, making it a sort of filter. This technique has some advantages. One is helping to narrowgrep's scope by searching through only the results of another process. For example, this command searches forianaonl...
8. Search a string Recursively in all Directories If you would like to search for a string in the current directory along with all of the subdirectories, you can specify the–roption to search recursively: # grep -r “function” *