All my scripting is done in Perl, I can execute one liners at the command line, and Perl regex seems way easier. Is there anything I can do in BASH that I can't do in Perl? I just don't feel like a true hacker unless I spend the time to delve in BASH and start using Sed and Awk as well. Is it worth it, or am I just asking for pain and...
I have a need to find all of the writable storage devices attached to a given machine, whether or not they are mounted. The dopey way to do this would be to try every entry in /dev that corresponds to a writable devices (hd* and sd*). Is there a better solution, or should I stick with this one? ...
I have two scripts that often need to be run with the same parameter: $ populate.ksh 9241 && check.ksh 9241 When I need to change the parameter (9241 in this example), I can go back and edit the line in history. But since I need to change the number in two places, I sometimes make a typo. I'd like to be able to change the parameter ...
I have an alert script that I am trying to keep from spamming me so I'd like to place a condition that if an alert has been sent within, say the last hour, to not send another alert. Now I have a cron job that checks the condition every minute because I need to be alerted quickly when the condition is met but I don't need to get the ema...
I need to search all cpp/h files in svn working copy for "foo", excluding svn's special folders completely. What is the exact command for GNU grep? ...
How do I do mv original.filename new.original.filename without retyping the original filename? I would imagine being able to do something like mv -p=new. original.filename or perhaps mv original.filename new.~ or whatever - but I can't see anything like this after looking at man mv / info mv pages. Of course, I could write a shell scri...
I currently do my textfile manipulation through a bunch of badly remembered awk, sed, bash and a tiny bit of Perl. I've seen mentioned a few places that python is good for this kind of thing, I know a little and I would like to know more. Is python a good choice for this, and is there a good book or guide to learning how to use python t...
Shell scripts are often used as glue, for automation and simple one-off tasks. What are some of your favorite "hidden" features of the Bash shell/scripting language? One feature per answer Give an example and short description of the feature, not just a link to documentation Label the feature using bold title as the first line See al...
I'm on OS X 10.5.5 (though it does not matter much I guess) I have a set of text files with fancy characters like double backquotes, ellipsises ("...") in one character etc. I need to convert these files to good old plain 7-bit ASCII, preferably without losing character meaning (that is, convert those ellipses to three periods, backqu...
What I want to do is the following: read in multiple line input from stdin into variable A make various operations on A pipe A without loosing delimiter symbols (\n,\r,\t,etc) to another command The current problem is that, I can't read it in with read command, because it stops reading at newline. I can read stdin with cat, like thi...
I have a file with fields separated by pipe characters and I want to print only the second field. This attempt fails: $ cat file | awk -F| '{print $2}' awk: syntax error near line 1 awk: bailing out near line 1 bash: {print $2}: command not found Is there a way to do this? ...
I have a command that runs fine if I ssh to a machine and run it, but fails when I try to run it using a remote ssh command like : ssh user@IP <command> Comparing the output of "env" using both methods resutls in different environment variables. When I manually login to the machine and run env, I get much more environment variables t...
Say I want to copy the contents of a directory excluding files and folders whose names contain the word 'Music'. cp [exclude-matches] *Music* /target_directory What should go in place of [exclude-matches] to accomplish this? ...
The following code number=1 if [[ $number =~ [0-9] ]] then echo matched fi works. If I try to use quotes in the regex, however, it stops: number=1 if [[ $number =~ "[0-9]" ]] then echo matched fi I tried "\[0-9\]", too. What am I missing? Funnily enough, bash advanced scripting guide suggests this should work. Bash version 3....
I want to find a linux command that can return a part of the string. In most programming languages, it's the substr() function. Does bash have any command that can be used for this purpose. I want to be able to do something like this... substr "abcdefg" 2 3 - prints 'cde' Subsequent similar question: http://stackoverflow.com/questio...
I currently use the following command, but it's a little unwieldy to type. What's a shorter alternative? find . -name '*.txt' -exec grep 'sometext' '{}' \; -print Here are my requirements: limit to a file extension (I use SVN and don't want to be searching through all those .svn directories) can default to the current directory, bu...
I want to pause input in a shell script, and prompt the user for choices. The standard 'Yes, No, or Cancel' type question. How do I accomplish this at a typical bash prompt? ...
Hello, I have a FreeBSD box with Bash set up. I'm used to Debian Linux where my command history is automatically saved when I log out, so that when I log back in I can press up or Ctrl-R or whatever and have access to my history. How do I set up Bash to do this on FreeBSD? ...
If I want to check for the null string I would do [ -z $mystr ] but what if I want to check whether the variable has been defined at all? Or is there no distinction in bash scripting? ...
Using bash, I have a string: string=`echo My string` How can I test if it contains another string? if [ $string ?? 'foo' ] then; echo "It's there!"; fi; Where ?? is my unknown operator. Do I use echo and grep? if [ `echo $string || grep 'foo' ` ] then; echo "It's there!"; fi; That looks a bit clumsy. ...