Programming :: Sed Substitution - Doesn't Appear To Be Capable Of Resolving Variables
Dec 21, 2008
I have a simple script that I am writing to parse an XML file for me, and update some version numbers. Basically what happens in my script is that I'm running a grep command on the file to get the current version number, then I prompt for a new number, and then I want to globally replace that version number in the file. The problem is, the sed command seems to only want literal values (it doesn't appear to be capable of resolving variables). For example, this code doesn't work:
[Code]...
I have tried removing the curly brackets from the variable names, quoting them, etc. and nothing seems to work. Should I do this with awk instead (and if so can you kindly write out the command for me because I never bothered to learn awk).
I set a variable before entering the FTP session (vDate). Then it does not seem to resolve when I try to use it in the session as part of an mput command. $vDate resolves as an empty value. Can you point me in the right direction?
I have 2 scripts that I copy from the material I study, one about working with environment variables and the other one about parsing command line output.
The problem with the first one is that the variables doesn't show after the script is run
The script syntax is as follows ( in short )
#! /bin/bash SYS_NAME=rhel01 OS_SYS="RHEL 05" export SYS_NAME OS_SYS echo " The hostname of this system is $SYS_NAME"
The variables are clean and available in my script. No prob. $old is an IP-address of a server, $new as well. replacement-file is an xml-file (the ip-address to be changed is within an xml-tag). It should be trivial, but it isn't. I spent the last 3 hours reading about the problem, trying several different 'solutions' or workarounds. It should work, the '"' should take care that the variables get expanded, but whatever I try the old server IP isn't replaced.
Just a simple BASH for loop to read the file path from a text file (clean.txt) echo the variable for debug purposes, and scp it to a server I have using port 50 for SSH.
I've already formatted the entries in clean.txt to handle spaces correctly, using sed replacement.
Example from the clean.txt file:
Code: /MP3/NAS000000001/Barenaked Ladies/Barenaked Ladies - Barenaked For The Holidays/20 Auld Lang Syne.mp3 /MP3/NAS000000001/Barenaked Ladies/Barenaked Ladies - Barenaked For The Holidays/14 Deck the Stills.mp3
file allids consists of 300,000 rows, each containing a 5-7 digit numeric id. file newids consists of 20,000 rows of id's. How do you explain the following timings? time: 0.07s:
I'm working on a program that will allow non-privileged users the ability to substitute passwords that are read in from a 600-root:root file. A user might call it like this: /bin/securepasswrapper "/path/to/check_ping -u Admin -p ?webserver1?"
The file (defined now as /tmp/securefile) will be searched for the identifier "webserver1", and it's corresponding password will be returned to securepasswrapper. Now, I know you could just call /bin/echo, and get the output, but that's in scope at this point. File format of securefile is: <identifierassword> ex: webserver1:asdf123
Once the password is properly substituted in, securepasswrapper should then execute it as the UID/EUID of the calling user (not root)...that part I've not got to yet. Code: /* program: securepasswrapper author: R.Briggs + Google date: 02/02/11 purpose: C wrapper that replaces placeholders in a string with secure passwords retrieved from a file */ .....
I have an interpteter that supports string literals, and the way it works is that the lexer returns the entire string as a single token, with the quotes removed and escape sequences replaced with the literal characters they represent.
I already implemented single-quote strings, they don't interpret any characters specially except for the single quote. I partially implemented double-quoted strings, they already support all the same backslash escape sequences that C does. But I would also want to add variable substitution.
The way it would work is that "${expression}" would interpret the expression (which could just be a variable name) and replace itself with the result. But I have no idea how to do this.
In case it matters, I'm using a hand-written lexer and recursive-descent parser.
Code: SERVERS=(SERVER1 SERVER2 SERVER3) SERVER1_SERV=(web ftp mail) SERVER2_SERV=(web transcoding) SERVER3_SERV=(web ftp mail) for SERVER in ${SERVERS[@]} do echo "Starting tranfer for server $SERVER" for SERVICE in ${$SERVER_$SERVICE[@]} do something_to_be_done fi done But when I run it I get ${$SERVER_$SERVICE[@]}: bad substitution
I remember reading that using sed, you can do this with parentheses: s/abc(something)def/(something)else/g I can't find an explanation of how to do something like this with Awk. Say you have this in an HTML file, where (number) stands for a one or two-digit number:
I need a substitution of a particular string (StringA) with another string (StringB). However, there may be more than one occurrence of StringA within the file, but only one instance needs to be changed, which is why I'm trying to be sure of it's positioning against something I know will be unique in the file, and will always have the same distance from the string to be replaced. So, I intend to match on a string (StringC) above the string to be substituted and then have sed go to StringA below and replace with StringB.
So far, I have had some success with the following:
Code:
... but I can't help thinking that there *has* to be a cleaner way of doing it.
if{ [catch {sqlite3 db /path/to/db/file} result] } { puts stderr $result } else { do something }
What I want is to use a variable for the file name/path. When I put in a variable instead of the absolute path, I get an error: "missing close-brace: possible unbalanced brace in comment while executing"
This is weird because when I run the code with the fully qualified pathname, it works fine. I substitute out the pathname for a variable containing the pathname ($variable) and I get this error.
Further to solved LQ thread Bash: how to populate a list of arbitrarily named files?, what is the functional difference between feeding a loop with process substitution and feeding it with a here string with embedded command substitution? ABSG pages: process substitution, here string and command substitution. This works
Code:
while IFS= read -r -d '' file do files+=("$file") done < <(find $dir -type f -print0)
I can find points to Tillies Garrels TLDP reference. Do I want to create my own variable to hold the string or do I want to place the string in memory? Is that my problem? Or is something different causing the 'bad substitution' error.
I can define all variables in tcl programming in a file for instance var.cfgand source the same file in my tcl script such assource var.cfgIs this possible in perl too?
When I execute something with sudo, the environment that it executes in doesn't have all the environment variables from /etc/profile{,.d/} defined. I googled around and found that there is a way to get the environment variables from the calling environment to be carried over to sudo's own environment, but that's not exactly what I want. I just want sudo to read the /etc/profile and /etc/profile.d/ before executing commands.
I'm trying to use ${VAR:0:4} substring extraction described here: tldp.org/LDP/abs/html/string-manipulation.html and it works perfectly if i issue a command in bash. But when i put it in a script file and run it, bash gives me "bad substitution" error. Does anyone know how to fix it?
I'm running into a problem when I try to set a variable to an awk output in c-shell. Right now my command is Code: set STR_MSG_TYPE = `awk -F{ '/msg_type/ {print $2}' <filename> | tr -d }'/''*' ` I then run echo to see what the output is and it returns blank, however, when I run the same awk command from the command line, I get an actual output of "MT-715". Am I setting my variable incorrectly? I do something similar using the date command to set a STR_DATE variable earlier in the code and it works fine and I use the same syntax.
i'm practicing in very basic c programs using the gcc compiler.I found that when i create two variables let's say
Code:
int a,b and Code: a=15; b=3; a=b; b--;
then a equals 2.I thought that this isn't normal in C isn't it?I haven't had the time to read the gcc documentation yet...so i think it has something to do with my compiler's default settings.I use the
Code: gcc filename.c -o filename command to compile
I have a C header file which have arrays of predefined(known) structure type. But i dont have names of arrays and their size. when i include that file and compile my application, i want to know the names and sizesof those arrays.
purpose of application is to get the content of those arrays and to explain it in descriptive words instead of hex numbers.ofcourse this can be done by file pointers and reading also with out header file inclusion, but as i am working in C, once compiled, those variables are in my address space in i include header file.
I am pretty new to PHP so excuse my dumbness. I've searched this up in quite a few places and cant find anything : Basically, I've made an array, within it are 3 more arrays. Their are two values in each array, 'Name' and 'Age'. Basically I am using a While statement to try and cycle through the 'age' value of my array and state whether or not the person is eligible. (I am actually just learning so I'm doing this to just test myself).
Here was an attempt to try and create a reference to age, I tried it many different ways while($age < 10) { echo ('$name, is eligible') ; } ?>
Okay, so I tried to do this through two ways, one way I tried to create a reference to age, then evaluate it, without that line of code their would be no reference, which way is correct, why wont it work? I am using Xammp, so when I launch local host I get an undefined variable error. What To Do?
My php knowledge is very poor (only worked with strings so far), and I am faced which a task that is a real challenge for me: I have a variable, that contains data of different type, in this order: byte, byte, string, string, string, string, short, byte, byte, byte, byte, byte, byte, byte, string.
Strings are of variable length. How could this data be parsed into variables of the right type, and then all converted to strings? What are the functions to use? Strings are unicode ones, and they are delimited by "
I just created a website in PHP and tested on my own webserver. All of my session variables worked great. Today I uploaded it to my commercial server host and it does not remember the session vars from one page to the next. Here is the session section of phpinfo().
Code: session Session Support enabled Registered save handlers files user sqlite Registered serializer handlers php php_binary wddx DirectiveLocal ValueMaster Value session.auto_startOffOff session.bug_compat_42OnOn session.bug_compat_warnOnOn session.cache_expire180180 session.cache_limiternocachenocache session.cookie_domainno valueno value session.cookie_httponlyOffOff session.cookie_lifetime00 session.cookie_path// session.cookie_secureOffOff session.entropy_fileno valueno value session.entropy_length00 session.gc_divisor100100 session.gc_maxlifetime14401440 session.gc_probability11 session.hash_bits_per_character44 session.hash_function00 session.namePHPSESSIDPHPSESSID session.referer_checkno valueno value session.save_handlerfilesfiles session.save_path/tmp/tmp session.serialize_handlerphpphp session.use_cookiesOnOn session.use_only_cookiesOffOff session.use_trans_sid00
You can see that session.save_path is set to /tmp, which is the default on the shared server. /tmp does exist in my document root directory.
Im a fresher in PHP.Actually i wanted to know that whether there will be time delay while using session variables in PHP.By using some 10-20 session variables in my code will it affect the speed of the loading of the page.If so then can u suuggest any other method to pass the varaibles which will not slow down the speed?
I have sles 10 . A user has a default shell of tcsh. I want to run a script which has to use ksh . In that script only some variables are exported, which will be used in subsequent scripts which are called inside it.
But the variables are not exported. I am unable to find whether its a conflict of shell or what ?? I tried with debug mode, it only displays the command but not execute anyone ..
I have a file that contains 5 fields and anothen one with two I want to take the value from user and search file1 and if the value exists then write in file2 to the $2 to the line that $1=value
