Linux: shell builtin string matching

Posted by gmatt on Stack Overflow See other posts from Stack Overflow or by gmatt
Published on 2010-04-30T16:39:22Z Indexed on 2010/04/30 16:47 UTC
Read the original article Hit count: 302

Filed under:

linux

|

wildcards

|

shell

|

parsing

I am trying to become more familiar with using the builtin string matching stuff available in shells in linux. I came across this guys posting, and he showed an example

a="abc|def"
echo ${a#*|}    # will yield "def"
echo ${a%|*}    # will yield "abc"

I tried it out and it does what its advertised to do, but I don't understand what the $,{},#,*,| are doing, I tried looking for some reference online or in the manuals but I couldn't find anything. Can anyone explain to me what's going on here?

© Stack Overflow or respective owner

Related posts about linux

apt-get install and update fail

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I've got a problem with apt-get update and apt-get install ... commands . every time update or installing fails and errors are : Get:1 http://dl.google.com stable Release.gpg [198B] Ign http://dl.google.com/linux/chrome/deb/ stable/main Translation-en_US Get:2 http://dl… >>> More
kernel module compiling error

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
sh@ubuntu:/home/ccpp/helloworld$ make gcc-4.6 -O2 -DMODULE -D_KERNEL_ -W -Wall -Wstrict-prototypes -Wmissing-prototypes -isystem /lib/modules/`uname -r`/build/include -c -o hello-1.o hello-1.c hello-1.c:4:0: warning: "MODULE" redefined [enabled by default] <command-line>:0:0: note: this is… >>> More
Build-Essentials installation failing

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I am having trouble accessing the several critical header files that show to be a part of the build process. The "Ubuntu Software Center" shows "Build Essentials" as installed: Next I did the following two commands, which did not improve the problem: ~$ sudo apt-get install build-essential [sudo]… >>> More
Updating Debian kernel

as seen on Super User - Search for 'Super User'
I'm trying to update my Debian machine to 2.6.32-46 (which is the new stable). However, after doing apt-get update my apt-cache search linux-image shows me: linux-headers-2.6.32-5-486 - Header files for Linux 2.6.32-5-486 linux-headers-2.6.32-5-686-bigmem - Header files for Linux 2.6.32-5-686-bigmem linux-headers-2… >>> More
Serial connection over a single USB cable (Windows to linux, or linux to linux)

as seen on Server Fault - Search for 'Server Fault'
I'm helping out with a project for an embedded device that only has USB and no serial. This device is running Linux. These days, when we need to connect to a serial port on a device we typically use a USB to serial adapter (on something like a phone system or a load balancing device, etc). I would… >>> More

Related posts about wildcards

E-mail hosting provider that can set up aliases with wildcards

as seen on Super User - Search for 'Super User'
I am looking for an e-mail hosting provider that allow e-mail aliases containing wildcards. In more detail: I own my own domain. I want an e-mail hosting provider to manager e-mail for my domain. Now, to help deal with spam, I often give different e-mail addresses to different organisations. These… >>> More
How do i write a sql query with user input and wildcards

as seen on Stack Overflow - Search for 'Stack Overflow'
Usually i write my where statements as WHERE key=@0 then add a param. Now i would like the user to specific a few letters such as 'oat' and would like to stick wildcards around it %oat% which matches 'coating'. So how do i write the query so wildcards are around the user input (the 'seachword'). Now… >>> More
how to insert many similar records in mysql at a time using phpmyadmin?

as seen on Super User - Search for 'Super User'
we know that we can insert multiple records at a time using this query: INSERT INTO `TABLE1` (`First`,`Last`) VALUES ('name1','surname1'), ('name2','surname2'), ('name3','surname3'), ('name4','surname4'); but what if we want to add 1000 similar records as above (name*,surname*) do we have to write… >>> More
Batch Script to Find Certain words and delete those lines in a file

as seen on Super User - Search for 'Super User'
EDITED THE QUESTION as regarding type of solutions I am on Windows & some suggested SED etc. So i am OK with these 3rd party standalone exe's using command line Say i have following lines in abc.txt file "@yuy007 what are you doing friend #disneyrocks" "STFU, i dont care what you think @happy55" "@social88… >>> More
Word mergefield wildcard not correctly matching

as seen on Super User - Search for 'Super User'
Hello, Below is my mergefield code: { IF { MERGEFIELD Subs_State } = "GA" "blah blah" "{ IF { MERGEFIELD CEOrgStates } = "GA" "blah blah" ""} "} I'm pulling records from a MS Access db. My goal is to check whether a record has Subs_State field matching "GA", or the CEOrgStates has the word "GA"… >>> More