I am trying to use Unix grep in my ruby code which I am able to run my shell terminal but it is not working when I am calling it through my ruby code. Can someone help me finding the problem?
I am trying to read the lines that match the pattern that starts with /platform/app_name and ends with username or service_name or hostname or port in config.txt file and write them into sub_config.txt file. Below is the piece of code that is blocking me right now.
exec ("cd #{$USER_HOME}; grep -E \'(^/platform/app_name/.*/username) | (^/platform/app_name/.*/port) | (^/platform/app_name/.*/service_name) | (^/platform/app_name/.*/hostname) \' config.txt > .sub_config.txt")
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I have very big text files(~50,000) over which i have to do some text processing. Basically run multiple grep commands.
When i run it manually it returns in an instant , but when i do the same in a bash script - it takes a lot of time. What am i doing wrong in below bash script. I pass the names of files as command line arguments to script
Example Input data :
BUSINESS^GFR^GNevil
PERSONAL^GUK^GSheila
Output that should come in a file - BUSINESS^GFR^GNevil
It starts printing out the whole file on the terminal after quite some while. How do i suppress the same?
#!/bin/bash
cat $2 | grep BUSINESS
Do NOT use cat with program that can read file itself.
It slows thing down and you lose functionality:
grep BUSINESS test | grep '^GFR|^GDE'
Or you can do like this with awk
awk '/BUSINESS/ && /^GFR|^GDE/' test
I'm working on a project, and it's being run by an autoscript. The script has the following line:
./executable ./dev | grep -i "GET.*index.*200" > ./dev/logs/log1
I have my code writing to stdout, but it never gets written to log1. If I change it though and remove the grep command, it writes just fine. Any help would be appreciated, as I seemingly don't understand grep as well as I should.
You might try to redirect std output in your script "executable" using commands:
exec > ./dev/logs/log1
exec 2> ./dev/logs/errlog1
So, now not need to use ">" in the line
./executable ./dev | grep -i "GET.*index.*200"
Also I recommend you to use only absolute paths in scripts.
ps. [offtop] I can't write comments yet (not enough reputation).
Sorry for the title, i couldn't find proper words to explain my problem.
Here's the code:
wlan_c=$(iwconfig | sed '/^\(w.*$\)/!d;s/ .*//' > ./wifi_iface)
wlan=$(<./wifi_iface)
echo "$wlan"
I get the following output:
lo no wireless extensions.
enp4s0 no wireless extensions.
wlp2s0
The last line is the result of execution the echo "$wlan".
The previous lines coming from the iwconfig, those that are not getting formatted by sed.
And the file ./wifi_iface also has the info i need.
Everything works as intended.
So i really want to get rid of that unwanted output before the wlp2s0 line.
How do i manage to do this?
That output must be going to stderr rather than stdout. Redirect it to /dev/null
iwconfig 2>/dev/null | sed '/^\(w.*$\)/!d;s/ .*//' > ./wifi_iface
There's no need to assign this to wlan_c. Since you're writing to the file, nothing will be written to stdout, so the assignment will always be empty.
I am facing issue with below command. When i am ruuning it is shell it is giving output.
count=`head -92 czh_script_178.log | tail -1 | sed 's/ //'`
But whenb I used it in shell script then it is failing with exit 0;
Can anyone please help in this.
I am using SunOS.
It looks like you want line 92 without some indentation. Here's how to do that:
count="$(sed -n '92s/^[[:space:]]*//p' /absolute/path/to/czh_script_178.log)"
If the path is not absolute in the script, it will fail unless $PWD is the same as the directory of the log file.
I'm pretty much a novice to shell scripting. I'm trying to send the output of some piped commands to an open command in bash in OSX.
My ultimate goal is to compile a Flex/Actionscript application from TextWrangler by calling a bash script with a little Applescript and have the result played directly in a Flash Player. The Applescript is pretty much doing it's job. But the bash script doesn't work as I expect. Same results when I ommit the Applescript and simply put it directly in terminal.
This is what the Applescript is sending to terminal:
mxmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//' | open -a 'Flash Player'
So basically, I read the last line of the output of mxmlc, which usually looks something like this:
/Users/fireeyedboy/Desktop/DocumentClass.swf (994 bytes)
and I strip everything after the first space it encounters. I know it's hardly bulletproof yet, it's still just a proof of concept. When I get this roughly working I'll refine. It returns the desired result so far:
/Users/fireeyedboy/Desktop/DocumentClass.swf
But as you can see, I then try to pipe this sed result to the Flash Player and that's where it fails. The Flash Player seems to open way too early. I would expect the Flash Player to open only after the script finished the sed command. But it opens way earlier.
So my question is twofold:
Is it even possible to pipe an
argument to the open command this
way?
Do I need to use some type
of delay command to get this
working, since the open command doesn't seem to be waiting for the input?
You're trying to give the name of the swf file as input to stdin of the open command, which it doesn't support.
It expects the file name as an argument (similar to -a).
You can do something like this:
FILENAME=`xmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//'`
open -a 'Flash Player' $FILENAME
or on a single line:
open -a 'Flash Player' `xmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//'`
If you're using bash (or another modern POSIX shell), you can replace the pretty unreadable backtick character with $( and ):
open -a 'Flash Player' $(xmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//')
All commands in a pipe are started at the same time. During this step, their input/outputs are chained together.
My guess is that open -a 'Flash Player' doesn't wait for input but simply starts the flash player. I suggest to try to run the player with an argument instead:
name=$(mxmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//')
open -a 'Flash Player' "$name"
I'm not familiar with the "open" command as it seems to be a mac thing, but i think what you want to do is:
open -a 'Flash Player' $(mxmlc -warnings=false DocumentClass.as | tail -n 1 | sed 's/[[:space:]].*$//')
In general you can't pipe arguments to a command, you have to specify that you want the output of the previous command to be treated as arguments, either as in my example or with the xargs command. Note that there is a limit on the maximum size of a command line, though.