[root@c7-server ~]#echo${name: -4}long 基于pattern取子串 这里的pattern,应该是glob或者类glob的,而非正则表达式,详见官方的Pattern Matching。 ${var#*pattern}:在变量var的值中自左向右查询pattern,若查询到,则删除值首部至第一次出现的pattern之间的所有字符。 [root@c7-server ~]#echo${name} zhangw...
Bash mainly offers two types of pattern matching:globsandextended globs.The two offer simple ways for users to select the filenames and check the different strings against specific rules. However, Bash also supports usingregex,especially when working with scripts to validate various user input and ...
13 echo "Number of characters in ${var1} = ${#var1}" 14 echo 15 16 echo "pattern1 = $pattern1" # a*c (everything between 'a' and 'c') 17 echo "---" 18 echo '${var1#$pattern1} =' "${var1#$pattern1}" # d12345abc6789 19 # 最短的可能匹配, 去掉abcd12345abc6789的...
functioncheckNumber{if[$1-eq5];thenecho'The number is 5'elif[$1-eq10];thenecho'The number is 10'elseecho'The number is not 5 or 10'fi}checkNumber5checkNumber10checkNumber15# Output:# 'The number is 5'# 'The number is 10'# 'The number is not 5 or 10' Bash Copy In this script...
Other features, e.g., history, are copied from csh and ksh. Bash is aPOSIX-compliant shell, but with a number of extensions. Explanation: grep '\b[Aa]\w*' filename.txt grep: This command searches text using patterns. '\b[Aa]\w*': This is the pattern to search for. ...
the operator is used as a pattern and pattern matching is performed. When the `=~'operator is used, the string to the right of the operatoris matched as a regular expression. The&& and || operatorsdonot evaluate EXPR2ifEXPR1 is sufficient to ...
The response to this command, especially when issued from the system root directory, contains too many entries for humans to parse easily. This is where pipes can come into play; in this case, the user can pipe the output from thelscommand to the Bash text pattern matching commandgrep. ...
中的参数扩展操作,# 符号在这里用于删除从左边开始匹配的第一个 _ 及其左边的所有字符。...所以,tmp 变量将被赋值为 "12345_subsequentchars.ext",去掉了原字符串中从左开始的第一个 _ 及其之前的 someletters 部分。...number=${tmp%_*}: 同样是 bash 的参数扩展操作,但这次 % 符号用于删除从右边开始匹...
-n, --line-number 输出的同时打印行号 --line-buffered 每行输出清空 -H, --with-filename 为每一匹配项打印文件名 -h, --no-filename 输出时不显示文件名前缀 --label=LABEL 将LABEL 作为标准输入文件名前缀 -o, --only-matching 只显示匹配PATTERN 部分的行 ...
Error: Invalid number of arguments Bonus: Bash if else statement in one line So far all the if else statement you saw were used in a proper bash script. That's the decent way of doing it but you are not obliged to it. When you just want to see the result in the shell itself, yo...