检查文件是否存在以及它是否包含特定字符串

Question

我想检查是否存在file2.sh，以及如果特定字poet是文件的一部分。我使用grep来创建变量used_var。

#!/bin/ksh 

file_name=/home/file2.sh     
used_var=`grep "poet" $file_name`  

如何检查used_var是否具有一定的价值？

Answer 1

test -e将测试文件是否存在。如果测试成功，则测试命令返回零值，否则返回1。

测试可以写无论是作为test -e或使用[]

[ -e "$file_name" ] && grep "poet" $file_name 

除非你真正需要的grep的输出，你可以测试返回值的grep会返回1，如果没有比赛和零，如果有是任何。

总体而言，你可以测试一个字符串是否非空使用[ "string" ]将返回0，如果非空则为1空

Answer 2

如果你有二进制安装test或ksh具有内置的匹配功能，你可以用它来执行你的检查。通常/bin/[是一个符号链接test：

if [ -e "$file_name" ]; then 
    echo "File exists" 
fi 

if [ -z "$used_var" ]; then 
    echo "Variable is empty" 
fi 

Answer 3

if test -e "$file_name";then 
... 
fi 

if grep -q "poet" $file_name; then 
    .. 
fi 

Answer 4

代替存储的grep的输出变量，然后检查是否变量是空的，你可以这样做：

if grep -q "poet" $file_name 
then 
    echo "poet was found in $file_name" 
fi 

============

以下是一些常用测试：

-d FILE 
      FILE exists and is a directory 
    -e FILE 
      FILE exists 
    -f FILE 
      FILE exists and is a regular file 
    -h FILE 
      FILE exists and is a symbolic link (same as -L) 
    -r FILE 
      FILE exists and is readable 
    -s FILE 
      FILE exists and has a size greater than zero 
    -w FILE 
      FILE exists and is writable 
    -x FILE 
      FILE exists and is executable 
    -z STRING 
      the length of STRING is zero 

例子：

if [ -e "$file_name" ] && [ ! -z "$used_var" ] 
then 
    echo "$file_name exists and $used_var is not empty" 
fi 

Answer 5

您应该使用grep-q标志安静输出。请参见下面的手册页：

人grep的输出：

General Output Control 

    -q, --quiet, --silent 
       Quiet; do not write anything to standard output. Exit immediately with zero status 
       if any match is found, even if an error was detected. Also see the -s or 
       --no-messages option. (-q is specified by POSIX.) 

这KornShell（KSH）脚本演示了grep安静的输出，是你的问题的解决方案。

grepUtil.ksh：

#!/bin/ksh 

#Initialize Variables 
file=poet.txt 
var="" 
dir=tempDir 
dirPath="/"${dir}"/" 
searchString="poet" 

#Function to initialize variables 
initialize(){ 
    echo "Entering initialize" 
    echo "Exiting initialize" 
} 

#Function to create File with Input 
#Params: 1}Directory 2}File 3}String to write to FileName 
createFileWithInput(){ 
    echo "Entering createFileWithInput" 
    orgDirectory=${PWD} 
    cd ${1} 
    > ${2} 
    print ${3} >> ${2} 
    cd ${orgDirectory} 
    echo "Exiting createFileWithInput" 
} 

#Function to create File with Input 
#Params: 1}directoryName 
createDir(){ 
    echo "Entering createDir" 
    mkdir -p ${1} 
    echo "Exiting createDir" 
} 

#Params: 1}FileName 
readLine(){ 
    echo "Entering readLine" 
    file=${1} 
    while read line 
    do 
     #assign last line to var 
     var="$line" 
    done <"$file" 
    echo "Exiting readLine" 
} 
#Check if file exists 
#Params: 1}File 
doesFileExit(){ 
    echo "Entering doesFileExit" 
    orgDirectory=${PWD} 
    cd ${PWD}${dirPath} 
    #echo ${PWD} 
    if [[ -e "${1}" ]]; then 
     echo "${1} exists" 
    else 
     echo "${1} does not exist" 
    fi 
    cd ${orgDirectory} 
    echo "Exiting doesFileExit" 
} 
#Check if file contains a string quietly 
#Params: 1}Directory Path 2}File 3}String to seach for in File 
doesFileContainStringQuiet(){ 
    echo "Entering doesFileContainStringQuiet" 
    orgDirectory=${PWD} 
    cd ${PWD}${1} 
    #echo ${PWD} 
    grep -q ${3} ${2} 
    if [ ${?} -eq 0 ];then 
     echo "${3} found in ${2}" 
    else 
     echo "${3} not found in ${2}" 
    fi 
    cd ${orgDirectory} 
    echo "Exiting doesFileContainStringQuiet" 
} 
#Check if file contains a string with output 
#Params: 1}Directory Path 2}File 3}String to seach for in File 
doesFileContainString(){ 
    echo "Entering doesFileContainString" 
    orgDirectory=${PWD} 
    cd ${PWD}${1} 
    #echo ${PWD} 
    grep ${3} ${2} 
    if [ ${?} -eq 0 ];then 
     echo "${3} found in ${2}" 
    else 
     echo "${3} not found in ${2}" 
    fi 
    cd ${orgDirectory} 
    echo "Exiting doesFileContainString" 
} 

#----------- 
#---Main---- 
#----------- 
echo "Starting: ${PWD}/${0} with Input Parameters: {1: ${1} {2: ${2} {3: ${3}" 
#initialize #function call# 
createDir ${dir} #function call# 
createFileWithInput ${dir} ${file} ${searchString} #function call# 
doesFileExit ${file} #function call# 
if [ ${?} -eq 0 ];then 
    doesFileContainStringQuiet ${dirPath} ${file} ${searchString} #function call# 
    doesFileContainString ${dirPath} ${file} ${searchString} #function call# 
fi 
echo "Exiting: ${PWD}/${0}" 

grepUtil.ksh输出：

user@foo /tmp 
$ ksh grepUtil.ksh 
Starting: /tmp/grepUtil.ksh with Input Parameters: {1: {2: {3: 
Entering createDir 
Exiting createDir 
Entering createFileWithInput 
Exiting createFileWithInput 
Entering doesFileExit 
poet.txt exists 
Exiting doesFileExit 
Entering doesFileContainStringQuiet 
poet found in poet.txt 
Exiting doesFileContainStringQuiet 
Entering doesFileContainString 
poet 
poet found in poet.txt 
Exiting doesFileContainString 
Exiting: /tmp/grepUtil.ksh