Hmm.. I am a little surprised with the difference in behaviour of `...` and $(...)
Edit
Ah ! Here's how it goes with the backticks.
Code:
[/tmp]$ abc=`echo "a/b/d" | sed 's#/#\\\\/#g'`
[/tmp]$ echo $abc
a\/b\/d
And here's why. From man sh
Code:
When the old-style backquote form of substitution is used, backslash
retains its literal meaning except when followed by $, ?, or \. The
first backquote not preceded by a backslash terminates the command sub-
stitution. When using the $(command) form, all characters between the
parentheses make up the command; none are treated specially.
When I create filesystems in AIX i often get confused(using smit)
When you specify size in aix, it is asked like this
SIZE of file system (in 512-byte blocks)
I never seem to grasp this, what is the equation to get say
500mb? Or is there a program anyone knows of that does this, like a... (1 Reply)
I want to convert string into uppercase string. How can i do that ? Ex: Enter the user name:
read name
show=upper(name)
echo $show --- This output should be the uppercase output.
Thanks (3 Replies)
I use Sco_Sv 3.2v5.0.5 with parellel conection using dump terminals and i want to convert them to desktop pc.
Anybody knows what hardware and other thing that would be involved? (3 Replies)
Hi - I have seen some similar posts but I am a bit stumped here
below is the first line of a 'od -c filename' command. I want to change the \0 to \n
0000000 l s \0 c d - \0 c d . . \0 l s
I have tried a sed construct in a script.........
sed... (2 Replies)
I have a file that ends with a ctlU:
> cat -v test.file
blah,blah,blah,GEAEA*1*xx0000111xxx^UIEA*xxx0^U
would like to replace the ctlU (^U) with a "\12"...due to printers or something.
I believe I might be able to utilize the tr command, if I could only identify the correct... (4 Replies)
I am having trouble parsing rpm filenames in a shell script.. I found a snippet of perl code that will perform the task but I really don't have time to rewrite the entire script in perl. I cannot for the life of me convert this code into something sed-friendly:
if ($rpm =~ /(*)-(*)-(*)\.(.*)/)... (1 Reply)
Hello folks
I have a txt file of information about journal articles from different fields. I need to convert this information into a format that is easier for computers to manipulate for some research that I'm doing on how articles are cited. The file has some header information and then details... (8 Replies)
I have Excel file with the below three columns, i need your expertise in converting this to .csv file delimiter "|"
Excel -
Serial Number Serial Name Serial Brand
111 test sample
123 test2 sample1
134 ... (9 Replies)
Discussion started by: kiran_hp
9 Replies
LEARN ABOUT MOJAVE
subst
subst(n) Tcl Built-In Commands subst(n)
__________________________________________________________________________________________________________________________________________________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(n), eval(n), break(n), continue(n)
KEYWORDS
backslash substitution, command substitution, variable substitution
Tcl 7.4 subst(n)