Sponsored Content
Top Forums Shell Programming and Scripting ksh - Get last character from string - Bad Substitution error Post 302900059 by alister on Saturday 3rd of May 2014 01:15:25 PM
Old 05-03-2014
Quote:
Originally Posted by bakunin
Yes - and no. "regular expressions" is (in a very theoretical sense) any type-3 language in the Chomsky hierarchy: a device where some characters and some metacharacters describe a text pattern. This is the case for shell regexps (aka "file globs") as well as for "Unix Basic Regular Expressions" (what awk, grep and sed use) or "Extended Regular Expressions" (i.e. perl and some GNU variants of grep, sed, ...). These are all different flavours of Regexps (and i should have mentioned that too, probably), but still Regexps nevertheless.
If we are going to be precise with regard to formal language theory, then you are mistaken. Neither POSIX Basic Regular Expressions, nor the "extended" dialects implemented in perl, python, php, java, et al, are regular expressions. Any grammar that supports backreferences cannot be implemented with a [non-]deterministic finite automaton (a defining characteristic of a regular language). sh pattern matching and POSIX Extended Regular Expressions, however, are formally regular languages.

As you noted, I was simply using conventional, informal nomenclature. The ksh/bash man pages make a concerted effort to not use the term 'regular expression' when discussing pattern matching notation.

Minor nit: AWK uses POSIX Extended Regular Expressions, not Basic.

Regards,
Alister
This User Gave Thanks to alister For This Post:
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

bad substitution Error while renaming Extension

Hi All, We are in the process of Migrating from AIX 4 to Solaris 10 and getting a Few Errors. I have been programming in shell but could never establish muself as an expert, hence please need you help. I am Getting Bad Substitution error in my script, I have isolated the issue and its... (6 Replies)
Discussion started by: paragkhanore
6 Replies

2. Shell Programming and Scripting

bad substitution error in ksh

hi, i created a shell script having the following content: #! /usr/bin/ksh FROM="myemail@domain.com" MAILTO="someemail@domain" SUBJECT="TEST" BODY="/export/home/adshocker/body.txt" ATTACH="/export/home/adshocker/attach.prog" echo $ATTACH ATTACH_NAME="${ATTACH##*/}" echo $ATTACH_NAME... (5 Replies)
Discussion started by: adshocker
5 Replies

3. Shell Programming and Scripting

bad substitution error in ksh

Hello, In bash I can use the following: TMP=12345 MID=${TMP:1:1} the expected result is: 2 but when using KSH I'm getting a ''bad substitution" error. What is the correct syntaxin ksh? Thanks (2 Replies)
Discussion started by: LiorAmitai
2 Replies

4. UNIX for Dummies Questions & Answers

bad substitution

#!/bin/bash a1=( win 12,01,02,03,04 ) a2=( pre 04,05,06 ) a3=( msn 06,07,08,09 ) Given the above arrays, I want the script to return/echo the following in a loop; win 12,01,02,03,04 pre 04,05,06,07 msn 06,07,08,09 But I can't get it to do as such. I've tried; (2 Replies)
Discussion started by: Muhammad Rahiz
2 Replies

5. Shell Programming and Scripting

KSH: substitution character, AWK or SED?

Hi Gurus, I am working with a korn shell script. I should replace in a very great file the character ";" with a space. Example: 2750;~ 2734;~ 2778;~ 2751;~ 2751;~ 2752;~ what the fastest method is? Sed? Awk? Speed is dead main point, Seen the dimensions of the files Thanks (6 Replies)
Discussion started by: GERMANICO
6 Replies

6. Shell Programming and Scripting

bad substitution error!

Hi All, I'm building a new shell script but i'm facing a problem with one line which is giving "bad substitution" error. Please assist script lines: #!/bin/sh printf "%s: " "Occurrence DATE (YYYYMMDD)"; read DATE shortdate=${DATE#??} o/p: ./test1: bad substitution This command is... (2 Replies)
Discussion started by: Dendany83
2 Replies

7. Shell Programming and Scripting

Why I get bad bad substitution when using eval?

Why I get bad replace when using eval? $ map0=( "0" "0000" "0") $ i=0 $ eval echo \${map$i} 0000 $ a=`eval echo \${map$i}` !!!error happens!!! bash: ${map$i}: bad substitution How to resolve it ? Thanks! (5 Replies)
Discussion started by: 915086731
5 Replies

8. Shell Programming and Scripting

Bad substitution error in shell script

I have script data.sh which has following error. Script Name : data.sh #!/bin/sh infile=$1 len=${#infile} echo $len texfile=${infile:0:$len-4} echo $texfile run command ./data.sh acb.xml I get following error message: (5 Replies)
Discussion started by: man4ish
5 Replies

9. Shell Programming and Scripting

Bad substitution error while working with substring

Hi I'm using ksh. And i'm trying to get the substring like below. but giving the following error #!/bin/ksh foo=teststring bar=${foo:0:5} echo $bar And the error is ./sbstr_test.sh: bar=${foo:0:5}: bad substitution what is wrong in this script. Please correct me ... (3 Replies)
Discussion started by: smile689
3 Replies

10. Shell Programming and Scripting

Bad substitution

Cant undestand :) why i have an error on line 2.it is working on my other boxes #!/bin/bash ret=$(echo Q | timeout 5 openssl s_client connect "${1`hostname`}:${2-443}" -ssl3 2> /dev/null) if echo "${ret}" | grep -q 'Protocol.*SSLv3'; then if echo "${ret}" | grep -q 'Cipher.*0000'; then ... (7 Replies)
Discussion started by: kenshinhimura
7 Replies
vgrindefs(5)						Standards, Environments, and Macros					      vgrindefs(5)

NAME
vgrindefs - vgrind's language definition data base SYNOPSIS
/usr/lib/vgrindefs DESCRIPTION
vgrindefs contains all language definitions for vgrind(1). Capabilities in vgrindefs are of two types: Boolean capabilities which indicate that the language has some particular feature and string capabilities which give a regular expression or keyword list. Entries may continue onto multiple lines by giving a as the last character of a line. Lines starting with # are comments. Capabilities The following table names and describes each capability. +-------+---------+--------------------------------------------+ |Name | Type |Description | +-------+---------+--------------------------------------------+ |ab | str |Regular expression for the start of an | | | |alternate form comment | +-------+---------+--------------------------------------------+ |ae | str |Regular expression for the end of an alter- | | | |nate form comment | +-------+---------+--------------------------------------------+ |bb | str |Regular expression for the start of a block | +-------+---------+--------------------------------------------+ |be | str |Regular expression for the end of a lexical | | | |block | +-------+---------+--------------------------------------------+ |cb | str |Regular expression for the start of a com- | | | |ment | +-------+---------+--------------------------------------------+ |ce | str |Regular expression for the end of a comment | +-------+---------+--------------------------------------------+ |id | str |String giving characters other than letters | | | |and digits that may legally occur in iden- | | | |tifiers (default `_') | +-------+---------+--------------------------------------------+ |kw | str |A list of keywords separated by spaces | +-------+---------+--------------------------------------------+ |lb | str |Regular expression for the start of a char- | | | |acter constant | +-------+---------+--------------------------------------------+ |le | str |Regular expression for the end of a charac- | | | |ter constant | +-------+---------+--------------------------------------------+ |oc | bool |Present means upper and lower case are | | | |equivalent | +-------+---------+--------------------------------------------+ |pb | str |Regular expression for start of a procedure | +-------+---------+--------------------------------------------+ |pl | bool |Procedure definitions are constrained to | | | |the lexical level matched by the `px' capa- | | | |bility | +-------+---------+--------------------------------------------+ |px | str |A match for this regular expression indi- | | | |cates that procedure definitions may occur | | | |at the next lexical level. Useful for lisp- | | | |like languages in which procedure defini- | | | |tions occur as subexpressions of defuns. | +-------+---------+--------------------------------------------+ |sb | str |Regular expression for the start of a | | | |string | +-------+---------+--------------------------------------------+ |se | str |Regular expression for the end of a string | +-------+---------+--------------------------------------------+ |tc | str |Use the named entry as a continuation of | | | |this one | +-------+---------+--------------------------------------------+ |tl | bool |Present means procedures are only defined | | | |at the top lexical level | +-------+---------+--------------------------------------------+ Regular Expressions vgrindefs uses regular expressions similar to those of ex(1) and lex(1). The characters `^', `$', `:', and `' are reserved characters and must be `quoted' with a preceding if they are to be included as normal characters. The metasymbols and their meanings are: $ The end of a line ^ The beginning of a line d A delimiter (space, tab, newline, start of line) a Matches any string of symbols (like `.*' in lex) p Matches any identifier. In a procedure definition (the `pb' capability) the string that matches this symbol is used as the procedure name. () Grouping | Alternation ? Last item is optional e Preceding any string means that the string will not match an input string if the input string is preceded by an escape character (). This is typically used for languages (like C) that can include the string delimiter in a string by escaping it. Unlike other regular expressions in the system, these match words and not characters. Hence something like `(tramp|steamer)flies?' would match `tramp', `steamer', `trampflies', or `steamerflies'. Contrary to some forms of regular expressions, vgrindef alternation binds very tightly. Grouping parentheses are likely to be necessary in expressions involving alternation. Keyword List The keyword list is just a list of keywords in the language separated by spaces. If the `oc' boolean is specified, indicating that upper and lower case are equivalent, then all the keywords should be specified in lower case. EXAMPLES
Example 1: A sample program. The following entry, which describes the C language, is typical of a language entry. C|c|the C programming language: :pb=^d?*?d?pd?(a?)(d|{):bb={:be=}:cb=/*:ce=*/:sb=":se=e": :le=e':tl: :kw=asm auto break case char continue default do double else enum extern float for fortran goto if int long register return short sizeof static struct switch typedef union unsigned void while #define #else #endif #if #ifdef #ifndef #include #undef # define endif ifdef ifndef include undef defined: Note that the first field is just the language name (and any variants of it). Thus the C language could be specified to vgrind(1) as `c' or `C'. FILES
/usr/lib/vgrindefs file containing vgrind descriptions SEE ALSO
ex(1), lex(1), troff(1), vgrind(1) SunOS 5.10 10 Aug 1994 vgrindefs(5)
All times are GMT -4. The time now is 10:56 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy