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|
+++
title = "bash"
disable_share = true
+++
# Test operators
## String
|op | desc | example |
|---|--------------------------------------------|-------------------------------------------|
|= |is equal to |`if [ "$a" = "$b" ]` |
|== |is equal to |`if [ "$a" == "$b" ]` |
|!= |is not equal to |`if [ "$a" != "$b" ]` |
|< |is less than, in ASCII alphabetical order |`if [[ "$a" < "$b" ]]; if [ "$a" \< "$b" ]`|
|> |is greater than, in ASCII alphabetical order|`if [[ "$a" > "$b" ]]; if [ "$a" \> "$b" ]`|
|-z |string is null, that is, has zero length |`if [ -z "$a" ]` |
## Integer
| op | desc | example |
| --- | ------------------------------------------------------- | ---------------------- |
| -eq | is equal to | `if [ "$a" -eq "$b" ]` |
| -ne | is not equal to | `if [ "$a" -ne "$b" ]` |
| -gt | is greater than | `if [ "$a" -gt "$b" ]` |
| -ge | is greater than or equal to | `if [ "$a" -ge "$b" ]` |
| -lt | is less than | `if [ "$a" -lt "$b" ]` |
| -le | is less than or equal to | `if [ "$a" -le "$b" ]` |
| < | is less than | `(("$a" < "$b"))` |
| <= | is less than or equal to | `(("$a" <= "$b"))` |
| > | is greater than | `(("$a" > "$b"))` |
| >= | is greater than or equal to | `(("$a" >= "$b"))` |
## File
| op | desc | example |
|---------|----------------------------------------------------------------------------------|-----------------------|
|-h |file is a symbolic link |`if [ -h "$f" ]` |
|-L |file is a symbolic link |`if [ -L "$f" ]` |
|-S |file is a socket |`if [ -S "$f" ]` |
|-t |file (descriptor) is associated with a terminal device |`if [ -t "$f" ]` |
|-r |file has read permission (for the user running the test) |`if [ -r "$f" ]` |
|-w |file has write permission (for the user running the test) |`if [ -w "$f" ]` |
|-x |file has execute permission (for the user running the test) |`if [ -x "$f" ]` |
|-g |set-group-id (sgid) flag set on file or directory |`if [ -g "$f" ]` |
|-u |set-user-id (suid) flag set on file |`if [ -u "$f" ]` |
|-k |sticky bit set |`if [ -k "$f" ]` |
|-O |you are owner of file |`if [ -O "$f" ]` |
|-G |group-id of file same as yours |`if [ -G "$f" ]` |
|-N |file modified since it was last read |`if [ -N "$f" ]` |
|f1 -nt f2|file f1 is newer than f2 |`if [ f1 -nt f2 "$f" ]`|
|f1 -ot f2|file f1 is older than f2 |`if [ f1 -ot f2 "$f" ]`|
|f1 -ef f2|files f1 and f2 are hard links to the same file |`if [ f1 -ef f2 "$f" ]`|
|! |"not" -- reverses the sense of the tests above (returns true if condition absent).|`if [ ! "$f" ]` |
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