检查文件是否存在并且是否包含特定字符串。

Question

我想检查file2.sh是否存在，并且也想检查文件中是否包含特定的单词poet。我使用grep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是否具有某个值？

- randeepsp

Answer 1

不必将grep的输出存储在变量中，然后检查变量是否为空，你可以这样做：

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

以下是一些常用的测试：

   -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

示例：

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

- dogbane

---

顺便提一下，-q是指"quiet"。 - br4nnigan

Answer 2

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

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

- ghostdog74

Answer 3

test -e命令用于测试文件是否存在。如果测试成功，该命令将返回零值，否则返回1。

可以使用test -e或[]来编写Test命令。

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

如果你不需要grep的输出，你可以测试它的返回值。如果没有匹配项，则grep将返回1，如果有任何匹配项，则返回0。

通常情况下，您可以使用[ "string" ]来测试字符串是否非空。如果非空，则返回0，如果为空则返回1。

- Steve Weet

Answer 4

如果你已经安装了 test 二进制文件或者 ksh 有一个匹配的内置函数，你可以使用它来执行你的检查。通常情况下，/bin/[ 是指向 test 的符号链接：

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

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

- joschi

Answer 5

你应该使用grep的-q标志以获得安静的输出。请参见下面的手册页面：

grep手册输出：

 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.)

这个KornShell（ksh）脚本演示了grep的安静输出，并且是你问题的解决方案。

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

- javaPlease42