What does this IF statement mean
Clash Royale CLAN TAG#URR8PPP
up vote
1
down vote
favorite
I have been trying to find online what these if statement mean. Below are a few.
if [ "$snums[k]" != "NA" -a ! -f "$aliases[k].4dfp.img" ]; then
if [ -f "$dcmfile" -a -n "`cat $dcmfile`" ]; then
The -a used in these two examples do not make senses to me.
linux bash
edited Jul 10 at 20:32
SivaPrasath
3,68311636
asked Jul 10 at 20:20
Aaron Tanenbaum
61
add a comment |Â
up vote
1
down vote
favorite
I have been trying to find online what these if statement mean. Below are a few.
if [ "$snums[k]" != "NA" -a ! -f "$aliases[k].4dfp.img" ]; then
if [ -f "$dcmfile" -a -n "`cat $dcmfile`" ]; then
The -a used in these two examples do not make senses to me.
linux bash
edited Jul 10 at 20:32
SivaPrasath
3,68311636
asked Jul 10 at 20:20
Aaron Tanenbaum
61
A good reason you may not have seen-aor-ois that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's&&and||instead
– Fox
Jul 10 at 23:20
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I have been trying to find online what these if statement mean. Below are a few.
if [ "$snums[k]" != "NA" -a ! -f "$aliases[k].4dfp.img" ]; then
if [ -f "$dcmfile" -a -n "`cat $dcmfile`" ]; then
The -a used in these two examples do not make senses to me.
linux bash
edited Jul 10 at 20:32
SivaPrasath
3,68311636
asked Jul 10 at 20:20
Aaron Tanenbaum
61
I have been trying to find online what these if statement mean. Below are a few.
if [ "$snums[k]" != "NA" -a ! -f "$aliases[k].4dfp.img" ]; then
if [ -f "$dcmfile" -a -n "`cat $dcmfile`" ]; then
The -a used in these two examples do not make senses to me.
linux bash
edited Jul 10 at 20:32
SivaPrasath
3,68311636
asked Jul 10 at 20:20
Aaron Tanenbaum
61
edited Jul 10 at 20:32
SivaPrasath
3,68311636
edited Jul 10 at 20:32
SivaPrasath
3,68311636
edited Jul 10 at 20:32
SivaPrasath
3,68311636
3,68311636
asked Jul 10 at 20:20
Aaron Tanenbaum
61
asked Jul 10 at 20:20
Aaron Tanenbaum
61
asked Jul 10 at 20:20
Aaron Tanenbaum
61
61
A good reason you may not have seen-aor-ois that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's&&and||instead
– Fox
Jul 10 at 23:20
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41
add a comment |Â
A good reason you may not have seen-aor-ois that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's&&and||instead
– Fox
Jul 10 at 23:20
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41
A good reason you may not have seen
-a or -o is that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's && and || instead– Fox
Jul 10 at 23:20
A good reason you may not have seen
-a or -o is that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's && and || instead– Fox
Jul 10 at 23:20
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
2
down vote
-a is logical AND. If both the operands are true, then the condition becomes true otherwise false.
-n Checks if the given string operand size is non-zero; if it is nonzero length, then it returns true.
answered Jul 10 at 20:34
SivaPrasath
3,68311636
1
And-fchecks if the following word is a regular file. Also, you can use-sto check if a file is not empty.
– l0b0
Jul 10 at 21:27
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
-a is logical AND. If both the operands are true, then the condition becomes true otherwise false.
-n Checks if the given string operand size is non-zero; if it is nonzero length, then it returns true.
answered Jul 10 at 20:34
SivaPrasath
3,68311636
1
And-fchecks if the following word is a regular file. Also, you can use-sto check if a file is not empty.
– l0b0
Jul 10 at 21:27
add a comment |Â
up vote
2
down vote
-a is logical AND. If both the operands are true, then the condition becomes true otherwise false.
-n Checks if the given string operand size is non-zero; if it is nonzero length, then it returns true.
answered Jul 10 at 20:34
SivaPrasath
3,68311636
1
And-fchecks if the following word is a regular file. Also, you can use-sto check if a file is not empty.
– l0b0
Jul 10 at 21:27
add a comment |Â
up vote
2
down vote
up vote
2
down vote
-a is logical AND. If both the operands are true, then the condition becomes true otherwise false.
-n Checks if the given string operand size is non-zero; if it is nonzero length, then it returns true.
answered Jul 10 at 20:34
SivaPrasath
3,68311636
-a is logical AND. If both the operands are true, then the condition becomes true otherwise false.
-n Checks if the given string operand size is non-zero; if it is nonzero length, then it returns true.
answered Jul 10 at 20:34
SivaPrasath
3,68311636
answered Jul 10 at 20:34
SivaPrasath
3,68311636
answered Jul 10 at 20:34
SivaPrasath
3,68311636
answered Jul 10 at 20:34
SivaPrasath
3,68311636
3,68311636
1
And-fchecks if the following word is a regular file. Also, you can use-sto check if a file is not empty.
– l0b0
Jul 10 at 21:27
add a comment |Â
1
And-fchecks if the following word is a regular file. Also, you can use-sto check if a file is not empty.
– l0b0
Jul 10 at 21:27
1
1
And
-f checks if the following word is a regular file. Also, you can use -s to check if a file is not empty.– l0b0
Jul 10 at 21:27
And
-f checks if the following word is a regular file. Also, you can use -s to check if a file is not empty.– l0b0
Jul 10 at 21:27
add a comment |Â
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f454561%2fwhat-does-this-if-statement-mean%23new-answer', 'question_page');
);
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
A good reason you may not have seen
-aor-ois that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's&&and||instead– Fox
Jul 10 at 23:20
Oh i see. I always thought -a was for checking to see if a file exists.
– Aaron Tanenbaum
Jul 11 at 15:41