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How to modify a global variable within a function in bash?
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This needs bash 4.1 if you use {fd} or local -n.
The rest should work in bash 3.x I hope. I am not completely sure due to printf %q - this might be a bash 4 feature.
Summary
Your example can be modified as follows to archive the desired effect:
# ...
Empty arrays seem to equal true and false at the same time
... JavaScript are truthy, so the convert any objects to Boolean is true. See 2ality.com/2013/08/objects-truthy.html
– Thomson
Oct 17 '16 at 21:27
add a comment
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Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]
...t with or without -n/-z is suitable for checking a variable.
| 1a 2a 3a 4a 5a 6a | 1b 2b 3b 4b 5b 6b
| [ [" [-n [-n" [-z [-z" | [[ [[" [[-n [[-n" [[-z [[-z"
-----+------------------------------------+------------------------------------
u...
How do you delete a column by name in data.table?
...ns
myVar = "foo"
df3[, (myVar):=NULL] # lookup myVar contents
# Method 2a -- A safe idiom for excluding (possibly multiple)
# columns matching a regex
df3[, grep("^foo$", colnames(df3)):=NULL]
# Method 2b -- An alternative to 2a, also "safe" in the sense described below
df3[, which(grepl("^foo$...
Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
...:
4004d6: 41 55 push r13
4004d8: 41 89 fd mov r13d,edi
4004db: 41 54 push r12
4004dd: 41 89 f4 mov r12d,esi
4004e0: 55 push rbp
4004e1: bd 00 c2 eb 0b ...
Multiple constructors in python? [duplicate]
...le, but I hope you get the idea:
class C(object):
def __init__(self, fd):
# Assume fd is a file-like object.
self.fd = fd
@classmethod
def fromfilename(cls, name):
return cls(open(name, 'rb'))
# Now you can do:
c = C(fd)
# or:
c = C.fromfilename('a filename')
...
Linux bpftrace学习笔记（持续更新） - 操作系统(内核) - 清泛网 - 专注IT技能提升
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Tracing open syscalls... Hit Ctrl-C to end.
PID COMM FD ERR PATH
4235 head -1 2 tls/x86_64/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/lib...
Linux bpftrace学习笔记（持续更新） - 操作系统(内核) - 清泛网 - 专注IT技能提升
.....
Tracing open syscalls... Hit Ctrl-C to end.
PID COMM FD ERR PATH
4235 head -1 2 tls/x86_64/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/lib...
Linux bpftrace学习笔记（持续更新） - 操作系统(内核) - 清泛网移动版 - ...
.....
Tracing open syscalls... Hit Ctrl-C to end.
PID COMM FD ERR PATH
4235 head -1 2 tls/x86_64/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/lib...
Linux bpftrace学习笔记（持续更新） - 操作系统(内核) - 清泛网 - 专注IT技能提升
.....
Tracing open syscalls... Hit Ctrl-C to end.
PID COMM FD ERR PATH
4235 head -1 2 tls/x86_64/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/x86_64/libc.so.6
4235 head -1 2 tls/lib...