${variable/pattern/string} # the longest match to pattern in variable is replaced by string. Only the first match is replaced ${variable//pattern/string} # the longest match to pattern in variable is replaced by string. All matches are replaced ${#varname} # returns the length of the va...
2.2 String Substitution 检查一些关于如何操作字符串的语法 ${variable#pattern}# if the pattern matches the beginning of the variable's value, delete the shortest part that matches and return the rest${variable##pattern}# if the pattern matches the beginning of the variable's value, delete the l...
2.2 String Substitution 检查一些关于如何操作字符串的语法 ${variable#pattern}# if the pattern matches the beginning of the variable's value, delete the shortest part that matches and return the rest${variable##pattern}# if the pattern matches the beginning of the variable's value, delete the l...
netstat -ant | grep 443 ### checking https status, if result is 1, it is running; if result is 0, https service is dead### ssl_status=`netstat -ant | grep 443 | wc -l` echo $ssl_status
变量替换(Variable Substitution)的代表符号。 vrs=123echo "vrs = $vrs" # vrs = 123 另外,在 Regular Expressions 里被定义为 "行" 的最末端 (end-of-line)。这个常用在grep、sed、awk 以及 vim(vi) 当中。${} 变量的正规表达式 bash 对 ${} 定义了不少用法。以下是取自线上说明的表列 ...
Read the bash manual page for the complete specification. String operators: -z STRING True if string is empty. -n STRING STRING True if string is not empty. 即,test命令使用-z STRING操作符来判断STRING字符串的长度是否为 0。 如果为 0,就是空字符串,会返回 true。
[root@www ~]# varname=aolens.com[root@www ~]# echo ${aolens.com}-bash:${aolens.com}:bad substitution[root@www ~]# echo ${varname}aolens.com[root@www ~]# echo "$varname"aolens.com[root@www ~]# echo '$varname'$varname ...
3. Pattern Matching and Substitution 3.1. Length We can access the length of a string using the hash (#) operator inside parameter expansion before the variable name: $ NAME=Baeldung $ echo ${#NAME} 8 3.2. Substrings We can extract a substring using the colon (:) operator inside the pa...
Fixed the bash command substitution warning using the lsdevinfo utility. Fixed boot-time bonding interface cleanup. (BZ#1853297) New kernel cmdline option now generates network device name The net_id built-in from systemd-udevd service gains a new kernel cmdline option net.naming- 17 Red Hat ...
/bin/bash /sbin/nologin 1. 2. 3. 二、 sort_wc_uniq命令 (1) sort sort 排序sort /etc/passwd 默认Assk 码 sort -t: -k3 /etc/passwd :分隔 最三段 sort -t: -k3 -n /etc/passwd n数字排序 sort -t: -k3,5 -n /etc/passwd 范围 ...