Can I say "${var##...}, ${var#...}, ${var%%...}, and ${var%...} only support the "*" "[0-9]" "[a-z]" "[A-Z", it seems others are not support " eg "." {3,}" "^" "$"
Thanks
Lei
Given the hints I've supplied so far, I'd expect that you'd be able to decode the bash man page to answer this. The example I gave above should work with any POSIX-conforming shell. I don't know of any shell where:
Code:
echo "${a##*[^0-9][0-9]{4}}"
will work. I use ksh for most of my shell programming. With ksh, but not bash:
Code:
echo "${a##*[^0-9]{4}([0-9])}"
will work.
If you can't figure out the bash man page and you don't want to restrict yourself to the set of portable shell constructs specified by the POSIX standard, you'll need to find someone else to help you.
Say I write something like the following:
var1=1
var2=2
for int in 1 2
do
echo "\$var$int"
done
I want the output to be:
1
2
Instead I get something like:
$var1
$var2 (2 Replies)
Hi,
What is the actual difference between these two? Why the following code works for process substitution and fails for command substitution?
while IFS= read -r line; do echo $line; done < <(cat file)executes successfully and display the contents of the file
But,
while IFS='\n' read -r... (3 Replies)
Hello,
in my .bashrc I tried to setup some aliases.
alias scp_cmd="scp -P 8888 $1 me@somehost:."
is supposed to copy a local file to somehost via scp. However it seems that the command line substitution does not work here. However this works:
alias lst="ls -l $1"
The above scp command can... (1 Reply)
Hi
I am looking for a unix command or a small shell script which can takes one parameter and then searches for the passed in the parameter in any or all files under say /home/dev/
Can anyone please help me on this? (3 Replies)
i am passing input parameter 'one_two' to the script , the script output should display the result as below
one_1two
one_2two
one_3two
if
then
echo " Usage : <$0> <DATABASE> "
exit 0
else
for DB in 1 2 3
do
DBname=`$DATABASE | awk -F "_" '{print $1_${DB}_$2}`
done
fi (5 Replies)
hi all,
i have a parameter file of following format, i want a method which can get the value of specific parameter.
parameter file format:
<Parameter Name="FileLocationWindows">
<Description>
The directory location of the logger file.
... (1 Reply)
Hi,
I have the following files.
->cat scr.sh
export TMP_DIR=/home/user/folder1
export TMP_DIR_2=/home/user/folder2
while read line
do
cat "$line"
done<file_list.dat
------------------------
-> cat file_list.dat
$TMP_DIR/file1.txt
$TMP_DIR_2/file2.txt
---------------------------
-> cat... (6 Replies)
Hi.
How do I achieve this
sh /EDWH-DMT02/script/MISC/exec_sql.sh "@/EDWH-DMT02/script/others/CSM_CKC/Complete_List.sql ${file_name}" Complete_List.txt
The /EDWH-DMT02/script/MISC/exec_sql.sh has two parameters and it's working fine with this
sh /EDWH-DMT02/script/MISC/exec_sql.sh... (7 Replies)
Can I specify a default value to a variable in AWK like BASH in one statement using parameter substitution?
BASH example:
argument=${$1-"default if empty"} (BASH)
I know I can do:
argument=$1; sub ( "^$", "default if empty", argument) (AWK)
Mike (13 Replies)
I am trying add a prefix variable(string) to command output.
sed parameter substitution is not working.
- I have found some issues on my end of testing,, please delete this thread for now. (1 Reply)
Discussion started by: kchinnam
1 Replies
LEARN ABOUT DEBIAN
subst
subst(3tcl) Tcl Built-In Commands subst(3tcl)__________________________________________________________________________________________________________________________________________________NAME
subst - Perform backslash, command, and variable substitutions
SYNOPSIS
subst ?-nobackslashes? ?-nocommands? ?-novariables? string
_________________________________________________________________DESCRIPTION
This command performs variable substitutions, command substitutions, and backslash substitutions on its string argument and returns the
fully-substituted result. The substitutions are performed in exactly the same way as for Tcl commands. As a result, the string argument
is actually substituted twice, once by the Tcl parser in the usual fashion for Tcl commands, and again by the subst command.
If any of the -nobackslashes, -nocommands, or -novariables are specified, then the corresponding substitutions are not performed. For
example, if -nocommands is specified, command substitution is not performed: open and close brackets are treated as ordinary characters
with no special interpretation.
Note that the substitution of one kind can include substitution of other kinds. For example, even when the -novariables option is speci-
fied, command substitution is performed without restriction. This means that any variable substitution necessary to complete the command
substitution will still take place. Likewise, any command substitution necessary to complete a variable substitution will take place, even
when -nocommands is specified. See the EXAMPLES below.
If an error occurs during substitution, then subst will return that error. If a break exception occurs during command or variable substi-
tution, the result of the whole substitution will be the string (as substituted) up to the start of the substitution that raised the excep-
tion. If a continue exception occurs during the evaluation of a command or variable substitution, an empty string will be substituted for
that entire command or variable substitution (as long as it is well-formed Tcl.) If a return exception occurs, or any other return code is
returned during command or variable substitution, then the returned value is substituted for that substitution. See the EXAMPLES below.
In this way, all exceptional return codes are "caught" by subst. The subst command itself will either return an error, or will complete
successfully.
EXAMPLES
When it performs its substitutions, subst does not give any special treatment to double quotes or curly braces (except within command sub-
stitutions) so the script
set a 44
subst {xyz {$a}}
returns "xyz {44}", not "xyz {$a}" and the script
set a "p} q {r"
subst {xyz {$a}}
returns "xyz {p} q {r}", not "xyz {p} q {r}".
When command substitution is performed, it includes any variable substitution necessary to evaluate the script.
set a 44
subst -novariables {$a [format $a]}
returns "$a 44", not "$a $a". Similarly, when variable substitution is performed, it includes any command substitution necessary to
retrieve the value of the variable.
proc b {} {return c}
array set a {c c [b] tricky}
subst -nocommands {[b] $a([b])}
returns "[b] c", not "[b] tricky".
The continue and break exceptions allow command substitutions to prevent substitution of the rest of the command substitution and the rest
of string respectively, giving script authors more options when processing text using subst. For example, the script
subst {abc,[break],def}
returns "abc,", not "abc,,def" and the script
subst {abc,[continue;expr {1+2}],def}
returns "abc,,def", not "abc,3,def".
Other exceptional return codes substitute the returned value
subst {abc,[return foo;expr {1+2}],def}
returns "abc,foo,def", not "abc,3,def" and
subst {abc,[return -code 10 foo;expr {1+2}],def}
also returns "abc,foo,def", not "abc,3,def".
SEE ALSO Tcl(3tcl), eval(3tcl), break(3tcl), continue(3tcl)KEYWORDS
backslash substitution, command substitution, variable substitution
Tcl 7.4 subst(3tcl)