A more lisible format of the command (with variable substitition made) :a
(0):label Marks a branch point to be referenced by the b and t subcommands.
This label can be any sequence of eight or fewer bytes.
Defines label a
$q
(1)q Branches to the end of the script. It does not start a new cycle.
$ means last line of input.
If last line of input, print the line and stop processing.
N
(2)N Appends the next line of input to the pattern space with an embedded
new-line character (the current line number changes). You can use this to search for patterns that are split onto two lines.
10,$D
(2)D Deletes the initial segment of the pattern space through the first new-line character and then starts the next cycle.
From line 10 to end, removes the oldest line (added by N command) at the begining of the buffer.
So the buffer contains all time at most 9 lines.
ba
(2)b[label] Branches to the : command bearing the label variable. If the label variable is empty, it branches to the end of the script.
Hello!
I want to read a file line by line and have each line in a variable. I have found the following code.
#!/bin/bash
exec 3< data
while read <&3
do echo "The number is $REPLY"
a.out "$REPLY"
done
exec 3>&-
I don't understand the use of exec and its arguments, though having read... (3 Replies)
Hi Friends,
I am trying to modify a script .The script contains this line:
sed -n -e 's_.*>\(.*\)<.*_\1_p' filename.xml
I am not great in sed command.I know, it is regular expression
to match a pattern string that starts with s_ and ends with 1_.I doesnot give the desired result.
Can... (4 Replies)
Hi all,
I'm very new to UNIX. I have got a coding, where i dont understand the below part. Could someone please explain it in detail?
awk 'NR > 1; NR == 1 { S = $0 } END { print S }' $textfile.bak > $textfile
could someone explain what
awk 'NR > 1; NR == 1 { S = $0 } END { print S }'
... (1 Reply)
sed '$!N; /^\(.*\)\n\1$/!P; D'
i found this file which removes duplicates irrespective for sorted or unsorted file. keep first occurance and remove the further occurances.
can any1 explain how this is working..
i need to remove duplicates following file. duplicate criteria is not the... (3 Replies)
Could someone explain why Python 3.1 errors out below? Do I need an additional module that's not required in 3.2 perhaps? I need to use 3.1 as it's the version available on a server I am using.
Python 3.2.1rc1 (default, May 18 2011, 11:01:17)
on linux2
Type "help", "copyright", "credits"... (0 Replies)
grep -E '^(++){5}5000' <file_name>
this command searches value 5000 in only 6th column from provided file where pipe ( | )is delimiter which separate columns... can some one plz explain me what '^(++){5}5000' actually does..? :confused: (1 Reply)
I had gone through..google search.....and unix user post.......where I found so many ways of accessing files..... suppose if I am having 4 files, each file is having 3 columns, and I want to use each field of each column, then how can I use it.. how can I create array for each file's each column,... (8 Replies)
#!/bin/bash
n=$l; typeset -a v
x=$(< input.dat)
check(){
if; then
sed 's/Test/Proc/g' file.sh >fl.sh
else
exit 13
fi
}
check $n
while ; do
x=`expr $x -l`
v=$x
done
less fi.sh l>/dev/null&& echo yes || exit 1
echo v= ${v
}
exit 0
I have file.sh and input.dat in the current... (3 Replies)
Discussion started by: bananasprite
3 Replies
LEARN ABOUT OPENDARWIN
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}} |
return ``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)