Here documents require that EOF is at the start of the on a separate line and that is the only text on the line, so using you code as an example, you would need something like this
Alternatively you could use a here-string
Passing a function is possible with bash through an export of the function, but can this easily become a security risk, so imho is best avoided.
For passing text to a sub process you can use a named pipe if you just want it to display the message,
or use bash 4's coproc functionality for a two-way pipe.
Last edited by Scrutinizer; 12-09-2017 at 07:09 AM..
"Is there any substituation of last command or script syntax which can be used as a user. As far I know the "last" command is being used to display information about previous logins. A member of adm group or the user adm can execute it only.
Thanks in advance for your usual help.
Ghazi (6 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)
I'm trying to get this to work and I'm not really sure how to do it.
echo $x | awk '{print $NF}' MODIFIEDThe output I'm trying to get should look like:
dir1 MODIFIED
Where dir1 will be the result of:
$x |awk '{print $NF}'I'm sure there's something I'm supposed to put around that part... (3 Replies)
I know this script is crummy, but I was just messing around.. how do I get sed's insert command to allow variable expansion to show the filename?
#!/bin/bash
filename=`echo $0`
/usr/bin/sed '/#include/ {
i\
the filename is `$filename`
}' $1
exit 0 (8 Replies)
Hey, guys!
Trying to research this is such a pain since the read command itself is a common word. Try searching "unix OR linux read command examples" or using the command substitution keyword. :eek:
So, I wanted to use a command statement similar to the following.
This is kinda taken... (2 Replies)
Hello Folks,
how to write a command on vi that allow to repeat last substitution command?
Here what I want to do :
1
2
3
1
2
3
1
2
3
:.,+2s/\n/ /And I obtain :
1 2 3
1
2
3
1 (5 Replies)
Hi,
I want to know if there's a cleaner way for assigning output of a unix command to a variable in C program .
Example : I execute dirname fname and want the output to be assigned to a variable dname . Is it possible .
I knew u can redirect the output to a file and then reread assigning... (5 Replies)
Hi,
I almost always use back quotes in scripts to assigin output of a command to a variable.
eg: file=`basename a/b/c/d/file`
year_mon=`date +%Y%m`
But the same can be achieved like:
file=$(basename a/b/c/d/file)
year_mon=$(date +%Y%m)
I would like to know if there is... (3 Replies)
I have the following code:
strfuture=abcdefghi
ver=${strfuture:${count}:1}
mj7777_ver=${ver} start_mj7777_iteration
let count=count+1
When it is executed I get bad substitution. The same if I use
ver=${strfuture:$count:1}
mj7777_ver=${ver}... (6 Replies)
Oracle Linux 5.6, 64-bit
Given the following snippet
wrkvar=`sqlplus -s / as sysdba <<EOF
set echo off feedback off head off trimsp on
select count(*) from v\$parameter
where name in ('db_file_name_convert','log_file_name_convert')
and value is not null;
EOF`
echo wrkvar=$wrkvarProduces... (2 Replies)
Discussion started by: edstevens
2 Replies
LEARN ABOUT CENTOS
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)