Why enclose a shell script in curly braces?
Clash Royale CLAN TAG#URR8PPP
up vote
3
down vote
favorite
What is the reason behind enclosing all lines in a shell script in curly braces?
e.g. the entire content of this script is enclosed in braces:
#!/bin/sh
set -e
LATEST="v0.3.5"
DGOSS_VER=$GOSS_VER
if [ -z "$GOSS_VER" ]; then
GOSS_VER=$GOSS_VER:-$LATEST
DGOSS_VER='master'
fi
GOSS_DST=$GOSS_DST:-/usr/local/bin
INSTALL_LOC="$GOSS_DST%//goss"
DGOSS_INSTALL_LOC="$GOSS_DST%//dgoss"
touch "$INSTALL_LOC"
Shellcheck.net deems the script valid with or without the curly braces.
shell-script shell
edited Mar 16 at 23:52
don_crissti
46.4k15123153
asked Mar 16 at 23:24
Zlemini
1736
add a comment |Â
up vote
3
down vote
favorite
What is the reason behind enclosing all lines in a shell script in curly braces?
e.g. the entire content of this script is enclosed in braces:
#!/bin/sh
set -e
LATEST="v0.3.5"
DGOSS_VER=$GOSS_VER
if [ -z "$GOSS_VER" ]; then
GOSS_VER=$GOSS_VER:-$LATEST
DGOSS_VER='master'
fi
GOSS_DST=$GOSS_DST:-/usr/local/bin
INSTALL_LOC="$GOSS_DST%//goss"
DGOSS_INSTALL_LOC="$GOSS_DST%//dgoss"
touch "$INSTALL_LOC"
Shellcheck.net deems the script valid with or without the curly braces.
shell-script shell
edited Mar 16 at 23:52
don_crissti
46.4k15123153
asked Mar 16 at 23:24
Zlemini
1736
1
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
2
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53
add a comment |Â
up vote
3
down vote
favorite
up vote
3
down vote
favorite
What is the reason behind enclosing all lines in a shell script in curly braces?
e.g. the entire content of this script is enclosed in braces:
#!/bin/sh
set -e
LATEST="v0.3.5"
DGOSS_VER=$GOSS_VER
if [ -z "$GOSS_VER" ]; then
GOSS_VER=$GOSS_VER:-$LATEST
DGOSS_VER='master'
fi
GOSS_DST=$GOSS_DST:-/usr/local/bin
INSTALL_LOC="$GOSS_DST%//goss"
DGOSS_INSTALL_LOC="$GOSS_DST%//dgoss"
touch "$INSTALL_LOC"
Shellcheck.net deems the script valid with or without the curly braces.
shell-script shell
edited Mar 16 at 23:52
don_crissti
46.4k15123153
asked Mar 16 at 23:24
Zlemini
1736
What is the reason behind enclosing all lines in a shell script in curly braces?
e.g. the entire content of this script is enclosed in braces:
#!/bin/sh
set -e
LATEST="v0.3.5"
DGOSS_VER=$GOSS_VER
if [ -z "$GOSS_VER" ]; then
GOSS_VER=$GOSS_VER:-$LATEST
DGOSS_VER='master'
fi
GOSS_DST=$GOSS_DST:-/usr/local/bin
INSTALL_LOC="$GOSS_DST%//goss"
DGOSS_INSTALL_LOC="$GOSS_DST%//dgoss"
touch "$INSTALL_LOC"
Shellcheck.net deems the script valid with or without the curly braces.
shell-script shell
edited Mar 16 at 23:52
don_crissti
46.4k15123153
asked Mar 16 at 23:24
Zlemini
1736
edited Mar 16 at 23:52
don_crissti
46.4k15123153
edited Mar 16 at 23:52
don_crissti
46.4k15123153
edited Mar 16 at 23:52
don_crissti
46.4k15123153
46.4k15123153
asked Mar 16 at 23:24
Zlemini
1736
asked Mar 16 at 23:24
Zlemini
1736
asked Mar 16 at 23:24
Zlemini
1736
1736
1
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
2
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53
add a comment |Â
1
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
2
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53
1
1
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
2
2
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
3
down vote
accepted
There is no obvious reason to do this. The curly braces is a grouping construct and the commands within them will be executed in the same environment as the rest of the script.
Had it been an ordinary parenthesis, then it would have been a sub-shell (a separate environment from the rest of the script), but in this instance that too would not have made much difference.
One possible reason for this is that it would enable the author to redirect all output from any command within the ... to some specific case, as in
...some commands...; >somefile
but this is obviously not done here.
With parenthesis,
( ...some commands... )
the author would have been able to set shell options and create local variables that don't affect the rest of the script.
answered Mar 17 at 8:24
Kusalananda
103k13201317
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with}; exit). That's also why some like to place their whole script in amainfunction.
– Stéphane Chazelas
Mar 17 at 8:33
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
There is no obvious reason to do this. The curly braces is a grouping construct and the commands within them will be executed in the same environment as the rest of the script.
Had it been an ordinary parenthesis, then it would have been a sub-shell (a separate environment from the rest of the script), but in this instance that too would not have made much difference.
One possible reason for this is that it would enable the author to redirect all output from any command within the ... to some specific case, as in
...some commands...; >somefile
but this is obviously not done here.
With parenthesis,
( ...some commands... )
the author would have been able to set shell options and create local variables that don't affect the rest of the script.
answered Mar 17 at 8:24
Kusalananda
103k13201317
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with}; exit). That's also why some like to place their whole script in amainfunction.
– Stéphane Chazelas
Mar 17 at 8:33
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
add a comment |Â
up vote
3
down vote
accepted
There is no obvious reason to do this. The curly braces is a grouping construct and the commands within them will be executed in the same environment as the rest of the script.
Had it been an ordinary parenthesis, then it would have been a sub-shell (a separate environment from the rest of the script), but in this instance that too would not have made much difference.
One possible reason for this is that it would enable the author to redirect all output from any command within the ... to some specific case, as in
...some commands...; >somefile
but this is obviously not done here.
With parenthesis,
( ...some commands... )
the author would have been able to set shell options and create local variables that don't affect the rest of the script.
answered Mar 17 at 8:24
Kusalananda
103k13201317
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with}; exit). That's also why some like to place their whole script in amainfunction.
– Stéphane Chazelas
Mar 17 at 8:33
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
add a comment |Â
up vote
3
down vote
accepted
up vote
3
down vote
accepted
There is no obvious reason to do this. The curly braces is a grouping construct and the commands within them will be executed in the same environment as the rest of the script.
Had it been an ordinary parenthesis, then it would have been a sub-shell (a separate environment from the rest of the script), but in this instance that too would not have made much difference.
One possible reason for this is that it would enable the author to redirect all output from any command within the ... to some specific case, as in
...some commands...; >somefile
but this is obviously not done here.
With parenthesis,
( ...some commands... )
the author would have been able to set shell options and create local variables that don't affect the rest of the script.
answered Mar 17 at 8:24
Kusalananda
103k13201317
There is no obvious reason to do this. The curly braces is a grouping construct and the commands within them will be executed in the same environment as the rest of the script.
Had it been an ordinary parenthesis, then it would have been a sub-shell (a separate environment from the rest of the script), but in this instance that too would not have made much difference.
One possible reason for this is that it would enable the author to redirect all output from any command within the ... to some specific case, as in
...some commands...; >somefile
but this is obviously not done here.
With parenthesis,
( ...some commands... )
the author would have been able to set shell options and create local variables that don't affect the rest of the script.
answered Mar 17 at 8:24
Kusalananda
103k13201317
answered Mar 17 at 8:24
Kusalananda
103k13201317
answered Mar 17 at 8:24
Kusalananda
103k13201317
answered Mar 17 at 8:24
Kusalananda
103k13201317
103k13201317
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with}; exit). That's also why some like to place their whole script in amainfunction.
– Stéphane Chazelas
Mar 17 at 8:33
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
add a comment |Â
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with}; exit). That's also why some like to place their whole script in amainfunction.
– Stéphane Chazelas
Mar 17 at 8:33
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
2
2
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with
}; exit). That's also why some like to place their whole script in a main function.– Stéphane Chazelas
Mar 17 at 8:33
A common reason for that is to guard against the script being overwritten while it's running (though you'd want to terminate it with
}; exit). That's also why some like to place their whole script in a main function.– Stéphane Chazelas
Mar 17 at 8:33
2
2
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
See How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:36
add a comment |Â
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1
The script you linked to does not have every line enclosed in curly braces. Could you please be more specific which uses you are asking about?
– Wildcard
Mar 16 at 23:31
It might be you're looking for unix.stackexchange.com/q/122845/135943, but it's hard to tell.
– Wildcard
Mar 16 at 23:32
Or possibly unix.stackexchange.com/a/306141/117549 or unix.stackexchange.com/q/164482/117549 or unix.stackexchange.com/a/148480/117549
– Jeff Schaller
Mar 16 at 23:45
2
Looks like it's from github.com/aelsabbahy/goss/commit/… ? I don't see any obvious reason to do that. Maybe ask the author?
– Mikel
Mar 16 at 23:47
A possible reason: How to read the whole shell script before executing it?
– Stéphane Chazelas
Mar 17 at 8:53