shell

问题 I've been using python for a long time. python's system and subprocess methods can take shell=True attibute to spawn an intermediate process setting up env vars. before the command runs. I've be using Java back and forth and using Runtime.exec() to execute shell command. Runtime rt = Runtime.getRuntime(); Process process; String line; try { process = rt.exec(command); process.waitFor(); int exitStatus = process.exitValue(); } I find difficulty to run some commands in java with success like

问题 I have a bash command that outputs text in the following format: Header 1 - Point 1 - Point 2 Header 2 - Point 1 - Point 2 Header 3 -Point 1 - Point 2 ... I want to parse this text into an array, separating on the empty line so that array[0] for example contains: Header 1 - Point 1 - Point 2 And then I want to edit some of the data in the array if it satisfies certain conditions. I was looking at something like this Separate by blank lines in bash but I'm completely new to bash so I don't

问题 I've read in multiple articles that semicolon( ; ) in UNIX-like shells is equal to a new line. However, the following is confusing me and I'm having no luck googling it either. I'm guessing it's an issue with do in shell, but "bash semicolon do" is not exactly the most google-friendly search term combination. Below is a simple for statement. for i in {1..10} do echo "hi" echo "bye" done As many Stack Overflow gurus have posted, every newline can be substituted with semicolons. So.. we have

问题 I'm trying to do an insert with sed (having just read up on it) and i'm being stumped by trying to insert multiple lines? What i'm currently doing is: sed -i "${line} i\ /* Name - ID */ \ select @ID = NULL \ from Animals \ where VrsnID = @VrsnID \ and Request= \"Request\" \ \ " animalNames.txt Note echo $line == 131 New Problem Everything appears on one line in the output? (also missing the first indent) /* Name - ID */ select @ID = NULL from Animals where VrsnID = @VrsnID and Request=

问题 I'm trying to do an insert with sed (having just read up on it) and i'm being stumped by trying to insert multiple lines? What i'm currently doing is: sed -i "${line} i\ /* Name - ID */ \ select @ID = NULL \ from Animals \ where VrsnID = @VrsnID \ and Request= \"Request\" \ \ " animalNames.txt Note echo $line == 131 New Problem Everything appears on one line in the output? (also missing the first indent) /* Name - ID */ select @ID = NULL from Animals where VrsnID = @VrsnID and Request=

问题 How to access bash positional parameter through a variable? e.g. I have a variable "pos", which can be anything between 1 to 6 (say). If pos==1 , I want to do: echo $1 If pos==2 , I want to do: echo $2 So on. Intuitively, I want to do something like: echo $$pos . I want to do it in one line. 回答1: Use variable indirection: echo "${!pos}" 回答2: Here are several solutions. Some may need a recent version of bash , others may still work with a very old one. Let us set up first our environment... $

问题 I need to assign the output of a command to a variable. The command I tried is: grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}' I try this code to assign a variable: UUID=$(grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}') However, it gives a syntax error. In addition I want it to work in a bash script. The error is: ./upload.sh: line 12: syntax error near unexpected token ENE=$( grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}

问题 I need to assign the output of a command to a variable. The command I tried is: grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}' I try this code to assign a variable: UUID=$(grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}') However, it gives a syntax error. In addition I want it to work in a bash script. The error is: ./upload.sh: line 12: syntax error near unexpected token ENE=$( grep UUID fstab | awk '/ext4/ {print $1}' | awk '{print substr($0,6)}

问题 I have the following files in the following format: $ ls CombinedReports_LLL-*'('*.csv CombinedReports_LLL-20140211144020(Untitled_1).csv CombinedReports_LLL-20140211144020(Untitled_11).csv CombinedReports_LLL-20140211144020(Untitled_110).csv CombinedReports_LLL-20140211144020(Untitled_111).csv CombinedReports_LLL-20140211144020(Untitled_12).csv CombinedReports_LLL-20140211144020(Untitled_13).csv CombinedReports_LLL-20140211144020(Untitled_14).csv CombinedReports_LLL-20140211144020(Untitled

问题 I have the following files in the following format: $ ls CombinedReports_LLL-*'('*.csv CombinedReports_LLL-20140211144020(Untitled_1).csv CombinedReports_LLL-20140211144020(Untitled_11).csv CombinedReports_LLL-20140211144020(Untitled_110).csv CombinedReports_LLL-20140211144020(Untitled_111).csv CombinedReports_LLL-20140211144020(Untitled_12).csv CombinedReports_LLL-20140211144020(Untitled_13).csv CombinedReports_LLL-20140211144020(Untitled_14).csv CombinedReports_LLL-20140211144020(Untitled