valint() #@ USAGE: valint INTEGER case ${1#-} in ## Leading hyphen removed to accept negative numbers *[!0-9]*) false;; ## the string contains a non-digit character *) true ;; ## the whole number, and nothing but the number esac 如果函数体用括号括起来,那么它是在子 shell ...
关键词do可以跟for写在同一行,两者使用分号分隔。for variable in list; do commands done下面是一个例子。#!/bin/bash for i in word1 word2 word3; do echo $i done上面例子中,word1 word2 word3是一个包含三个单词的列表,变量i依次等于word1、word2、word3,命令echo $i则会相应地执行三次。
# check if $1 does indeed contain only characters a-z,A-Z { # assign the argument across to new variable _LETTERS_ONLY=$1 _LETTERS_ONLY=`echo $1 | awk '{if($0~/[^a-zA-Z]/) print "1"}'` if [ "$_LETTERS_ONLY" != "" ] then # oops errors return 1 else # contains onl...
# remove the last character in string and return it in $rval if [ -z "$1" ]; then # empty string rval="" return fi # wc puts some space behind the output this is why we need sed: numofchar=`echo -n "$1" | wc -c | sed 's/ //g' ` if [ "$numofchar" = "1" ]...
# of the LINENO environment variable. It contains the current # line number. echo"Example of error with line number and message" error_exit"$LINENO: An error has occurred." 在bash脚本中有更好的错误处理例程吗? 相关讨论 请参阅这个详细的答案:在bash脚本中引发错误。
To check if a Bash array contains a value, use the echo command and pipe it to grep command to search the value from the defined array.
sexit status. The exit status of a program is an integer which indicates whether the program was executed successfully or if an error occurred. The exit status of the last program run is stored in the question mark variable ($?). We can take a look at the exit status of the last ...
Bash Write Variable to File Print Every nth Line from File in Bash If Not Condition in Bash Remove Character from String in Bash Convert Array to Comma Separated String in Bash Get Last Word in Each Line in Bash Check If Output Contains String in Bash sed Remove Leading and Trailing Whitesp...
How to check if a variable exists or is “null”? How to check if a file exists? How to check if a directory exists? How to check if a command succeeds or failed? How to do string comparison and check if a string equals to a value? How to check if a string is in an array?
When no array variable name is provided to the mapfile command, the input will be stored into the $MAPFILE variable. Note that the mapfile command will split by default on newlines character but will preserve it in the array values, you can remove the trailing delimiter using the -t ...