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Full Discussion: Loop breaks through ssh in script
Operating Systems AIX Loop breaks through ssh in script Post 302875015 by bakunin on Monday 18th of November 2013 09:40:00 AM
Old 11-18-2013
Quote:
Originally Posted by omonoiatis9
i use the backticks because this way i tell the script if the command inside the backticks executes successfully then proceed. else if the command fails it doesnt get into the if statement.
No, no and again: no.

First, the "if"-statement:

The if-statement is defined as:
Code:
if command ; then commandA ; else commandB ; fi

command can be any command, simple or complex. In either way its return code is used to determine if the then-branch or the else-branch is executed. If the return code ("$?") is 0 (zero), the then-branch is executed, otherwise the else-branch.

The probably most often-used command in this position is /usr/bin/test or its counterpart /usr/bin/[. Both work the same way (the difference being that "[" requires "]" as the last argument): if the tests specified as arguments add up to a boolean TRUE it returns 0, for a boolean FALSE it returns 1.

Still, the same way as you use test you can use any other command. For instance:

Code:
if grep -q EXPR /some/file ; then

will execute the then-branch if EXPR is found in /some/file and the else-branch if not, because grep will return 0 if it finds what is searched for and 1 if it doesn't.

Second: the backticks.

Even if you need process substitution (which isn't the case, see above), you should NOT use backticks - not the last 20 years or so. Even ksh88 already had "$(...)" instead of "`...`", which is not only nestable, but also the POSIX-compatible way to enclose a process. Backticks are supported only for one reason: backwards compatibility. There is absolutely no reason to use them any more, because they offer absolutely no advantage over "$(...)", only drawbacks.

I hope this helps.

bakunin
 

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LEARN ABOUT DEBIAN

stg-publish

STG-PUBLISH(1)							   StGit Manual 						    STG-PUBLISH(1)

NAME

       stg-publish - Push the stack changes to a merge-friendly branch

SYNOPSIS

       stg publish [options] [branch]

DESCRIPTION

       This command commits a set of changes on a separate (called public) branch based on the modifications of the given or current stack. The
       history of the public branch is not re-written, making it merge-friendly and feasible for publishing. The heads of the stack and public
       branch may be different but the corresponding tree objects are always the same.

       If the trees of the stack and public branch are different (otherwise the command has no effect), StGit first checks for a rebase of the
       stack since the last publishing. If a rebase is detected, StGit creates a commit on the public branch corresponding to a merge between the
       new stack base and the latest public head.

       If no rebasing was detected, StGit checks for new patches that may have been created on top of the stack since the last publishing. If new
       patches are found and are not empty, they are checked into the public branch keeping the same commit information (e.g. log message, author,
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       If the above tests fail (e.g. patches modified or removed), StGit creates a new commit on the public branch having the same tree as the
       stack but the public head as its parent. The editor will be invoked if no "--message" option is given.

       It is recommended that stack modifications falling in different categories as described above are separated by a publish command in order
       to keep the public branch history cleaner (otherwise StGit would generate a big commit including several stack modifications).

       The public branch name can be set via the branch.<branch>.public configuration variable (defaulting to "<branch>.public").

OPTIONS

       -b BRANCH, --branch BRANCH
	   Use BRANCH instead of the default branch.

       --author "NAME <EMAIL>"
	   Set the author details.

       --authname NAME
	   Set the author name.

       --authemail EMAIL
	   Set the author email.

       --authdate DATE
	   Set the author date.

       -m MESSAGE, --message MESSAGE
	   Use MESSAGE instead of invoking the editor.

       -f FILE, --file FILE
	   Use the contents of FILE instead of invoking the editor. (If FILE is "-", write to stdout.)

       --sign
	   Add a "Signed-off-by:" to the end of the patch.

       --ack
	   Add an "Acked-by:" line to the end of the patch.

STGIT

       Part of the StGit suite - see linkman:stg[1]

StGit								    03/13/2012							    STG-PUBLISH(1)
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